From: gazissax@netcom.com
Newsgroups: misc.kids.info,misc.answers,news.answers
Subject: misc.kids FAQ on Childhood Vaccinations, Part 2/4
Followup-To: misc.kids.health
Approved: news-answers-request@MIT.EDU, kids-info-request@ai.mit.edu
Reply-To: gazissax@netcom.com
Summary: This FAQ contains information on vaccinations, with particular
        focus on the vaccinations given to children.  Section 2 contains 
	information about the vaccines which are on the required vaccination 
	schedule within the USA.

Archive-name: misc-kids/vaccinations/part2
Posting-Frequency: monthly
Last-Modified: October 23, 1999

Q3a.1 What is diptheria, and what are the risks of the disease?

Diptheria is a contagious disease affecting the nose, throat, and skin. Complications include paralysis (about 20% of patients) and heart damage (about 50%) (Pantell, Fries, and Vickery). The Merck manual has a very long list of complications, mostly involving the heart, and says that complications are likely if antitoxin isn't administered properly. The death rate was 35% before antitoxin was available, and is now 10% (Harrison).

Q3a.2 How common was diptheria before routine vaccination, and how common is it now?

In 1900, there were 40.3 deaths per 100,000 population from diptheria in the US. There was a sharp decline in the number of deaths per 100,000 both before and after routine vaccination was instituted in the 1940s, and in 1990 there were 4 cases of diptheria reported in the US. (_Historical Statistics of the United States, Colonial Times to 1970_ and _Statistical Abstracts of the United States_.

In Europe, there were large diptheria epidemics during and after World War II, with an estimated one million cases and 50 000 deaths in 1943 (source: WHO web page on diptheria, written March 1998, http://www.who.org/gpv-dvacc/diseases/diphtheria_dis.htm). More recently, there have been large epidemics in Russia and the Newly Independent States.

Q3a.3 How effective is the diptheria vaccine?

"The fatality rate in immunized populations is one-tenth that in the unimmunized population. Paralysis is 5 times and 'malignant' disease 15 times less common in immune than in nonimmune individuals." (Harrison)

Q3a.4 How long does the diptheria vaccine last?

Ten years.

Q3a.5 What is pertussis, and what are the risks of the disease?

Pertussis, or whooping cough, is a very contagious disease of the respiratory tract. Its attack rate in unvaccinated household contacts is over 90% (PDR) or up to 90 and in some cases 100% (Harrison).

Pertussis is very serious in children under 2, with a mortality rate on about 1 to 2%. (Merck) "Prior to the availability of a vaccine, pertussis caused as many deaths as all other contagious disease _combined_." (Harrison, p. 607) Complications include various lung complications (The Merck Manual has a long list of these), cerebral complications, hemorrage into the brain, eyes, skin, and mucuous membranes. In addition to killing, it can leave surviving infants with lasting lung damage and neurological diseases.

The mortality rate is higher in developing countries, partly because children in these countries contract pertussis at a younger age (and mortality is higher at younger ages), and partly due to an association with protein-energy malnutrition (Galazka). This same article estimated that in the industrialized world, 0.04% of infected children die from pertussis and complications, usually pneumonia "Among vaccine-preventable diseases, pertussis rivals measles and neonatal tentanus in importance and severity in young children in developing countries and is third only to measles and neonatal tetanus as a cause of death. It is estimated that pertussis is still causing some 340,000 deaths of children in the world each year." (Galazka)

Q3a.6 How common was pertussis before routine vaccination, and how common is it now?

[Note: This section may be outdated, since the introduction of the new acellular vaccine has caused changed in vaccination schedules and vaccination coverage. More recent information on international vaccine schedules and disease incidence may be found at http://www.who.org.)

"Since immunization against pertussis (whooping cough) became widespread, the number of reported cases and associated mortality declined from about 120,000 cases and 1,100 deaths in 1950, to an annual rate of about 3,500 cases and 10 fatalities in recent years." (PDR) For unknown reasons, there has been an increase in the US recently. "Over 6000 cases of pertussis were reported in the U.S. in 1993, the highest number in 25 years." (N Engl J Med 1994 Jul 7; 331:16-21, summarized in Journal Watch for July 22, 1994.) There is also a recent report (MMWR Nov 11, p. 807) of a strain of pertussis resistant to erythromycin.

In some other countries, pertussis is more common (most of the following information is taken from Galazka). "Before the introduction of widespread immunization of young children with pertussis vaccine, the incidence rates in Europe and the United States were very high. The reported rates per 100,000 population ranged from 200-300 in England and Wales and Sweden, to more than 1,000 in Denmark and Norway." (Galazka) Annual incidence in the US and Canada before the introduction of pertussis vaccine in the 1940s ranged from 98 to 210 per 100,000 population. After the introduction and widespread use of DTP vaccine, incidence declined dramatically in most countries, and this trend continued for about 20 years. For example, in England and Wales, more than 150,000 cases of pertussis were reported a year in the 1950s; by 1973, when vaccine acceptance was over 80%, only about 2,400 cases were reported.

However, in the late 1970s and the 1980s, different trends began to appear in different European countries. In one group of countries, reported incidence is between 10 and >100 per 100,000. This group includes Sweden and Italy, which don't routinely give pertussis vaccine to infants. It also includes Germany, the former USSR, Ireland, Spain, and the United Kingdom, where infants are routinely vaccinated, but coverage is less than 80%. In Denmark, incidence is high despite high coverage, but Denmark uses a different vaccination schedule from the other countries. Countries with a moderate reported incidence (between 1 and 10 per 100,000) include Austria, Finland, Greece, Israel, Norway, the Netherlands, Portugal, Romania, and Yugoslavia. Countries with a low incidence (less than 1 per 100,000) include Hungary, Switzerland, Bulgaria, Czechoslovakia, Poland, and Turkey.

Q3a.7 How effective is the whole cell pertussis vaccine?

It's one of the less effective childhood vaccinations. The PDR estimates its effectiveness at 70-80%. It's effectiveness rating depends on the severity of the cases of pertussis being observed. One study of 1797 households found the vaccine to be 64% effective against a mild cough, 81% effective against a paroxysmal cough, and 95% effective against severe clinical illness. "Requiring laboratory confirmation improved efficacy to 95 to 98% for culture-positive children and to 77% to 95% for culture- or serology-confirmed cases, depending on disease severity. Vaccine efficacy for typical paroxysmal cough increased from 44% for one diptheria, tetanus, and pertussis vaccine to 80% for four or more doses." (Onorato, Wassilak, and Meade) The variation in estimates of efficacy may be because the more severe cases were more likely to actually be pertussis, or it may be that the vaccine protects better against severe pertussis than against a mild form of the disease. Note: these effectiveness ratings are for the older, whole cell pertussis vaccine. For information on the effectiveness of the newer, acellular vaccines, which is generally comparable to that of the older whole cell vaccines, see below.

Q3a.8 How long does the pertussis vaccine last?

It doesn't. According to _Harrison's Internal Medicine_, "the protection ... is transient, with minimal resistance being evident a decade later." However, the critical years for pertussis immunity are when a child is young; the disease is not dangerous for adults. With introduction of the new, less reactogenic acellular vaccine, it is possible that boosters may eventually be given to adults. (This estimate is for the older, whole cell vaccine, but the newer acellular vaccine is apparently at least as durable as the whole cell one was.)

Q3a.9 What is tetanus, and what are the risks of the disease?

Tetanus is very dangerous. Even with antibiotics, mortality can be 40% or higher (Pantell, Fries, and Vickery, Harrison). Tetanus bacteria and its spores are everywhere. Because tetanus is so ubiquitous, the only way to counter it is widespread vaccination.

*************************************************************************
From J Thompson (jet14@columbia.edu):

    The tetanus vaccine is actually against the tetanus toxin (a protein
called tetanospasmin), rather than the bacterium alone. The bacterium
doesn't really do much of significance, but the toxin it secretes can cause
muscular spasms. Thus, antibiotic therapy is rather pointless in preventing
the spasms, but it is given anyway. The administration of antitoxin (passive
immunity) is helpful. (see Harrison's, 13th ed., p. 635)
    The vaccine consists of what is called "tetanus toxoid," which is simply
 a purified version of the toxin, which has been treated to render it
ineffective as a toxin (but still immunogenic).
*************************************************************************

Q3a.11 How effective is the tetanus vaccine?

According to Taking Care of Your Child, "Tetanus is one of our best immunizations.... Of all the vaccines available, tetanus comes closest to 100 percent effectiveness after the initial series of shots."

Q3a.12 How long does the tetanus vaccine last?

Generally ten years. In the case of a really dirty wound, a booster is recommended if the person hasn't been vaccinated for tetanus within the last five years.

Q3a.13 What are some of the risks of the DTP vaccine?

DTP, particularly in its earlier form (with the whole cell pertussis component) is probably the most controversial of the childhood vaccines, because of risks associated with its pertussis component. Anecdotal evidence has linked the vaccine with a variety of problems, including convulsions, physical collapse, brain damage and SIDS. Supporters of the vaccine have argued that these problems are common in any case at the age at which children are vaccinated for pertussis, and therefore are not necessarily effects of the vaccine.

The association between DTP and SIDS has not been confirmed by further study (see Q1.5 for a study which found the evidence to be against such an association). The story on brain damage is somewhat different. Criticism of the pertussis vaccine received some confirmation in 1976, when a large British study of all children 2 to 36 months old in Britain found that 1 in 310,000 doses resulted in permanent brain damage.

Critics argue that the rate of complications from the pertussis vaccine is too high, and the effectiveness too low. Some argue that the decline in pertussis cases in this century has been an effect more of improved sanitation than of the pertussis vaccine. The side effects of this vaccine have inspired groups critical of vaccination in several countries, including the US, where the group Dissatisfied Parents Together (DPT) has lobbied Congress for changes to laws about vaccination and set up its own vaccine information center.

Supporters of the pertussis vaccine differ in their response to the British study which linked pertussis to brain damage. Some say that further analysis indicates that a link between the vaccine and brain damage is not so clear. "Meticulous reexamination of the data from this study led to the conclusion that the preliminary results were due to a systematic bias that favored finding an association between the vaccine and serious neurological sequelae. In fact, there was no valid evidence from the study that the vaccine was associated with permanent neurological damage." (Shapiro)

Some smaller studies done since the British study didn't find a connection between DTP vaccine and neurological damage, and a new study was just published in the Journal of the American Medical Association which finds no increased risk of serious neurological illness. I haven't seen the article yet, so my information comes from the January 11, 1994 San Jose Mercury (from the New York Times news service), which reports that the study is in the current (as of 1/11/94) issue of JAMA. According to the article, "The federally financed study, the largest of its kind in the United States, involved 218,000 children up to 24 months old in Oregon and Washington who were studied for a one-year period, beginning Aug. 1, 1987." However, the study is also described as "not intended to give a definitive answer to the question of whether whooping cough vaccine causes neurological illness."

Others do not dispute the 1976 British study, but argue that a 1 in 310,000 risk of brain damage is still much smaller than the risk of actually getting pertussis. Supporters agree that it is important to maintain high vaccination levels against pertussis, lest we see a resurgence in the disease. In Great Britain, Japan, and Sweden, there were sharp increases in the number of cases of pertussis when vaccination levels fell. Routine use was discontinued in Sweden as a result of reports of side effects, while acceptance in Great Britain declined to 30% (Harrison), and vaccination declined in Japan as well. "Within two years, one hundred thousand cases (with twenty-eight deaths) appeared in Great Britain and thirteen thousand cases (with forty-one deaths) in Japan. Even in the US, the disease has by no means been wiped out; there are still about fifteen hundred to two thousand cases (with four to ten deaths) each year. That is why virtually all health care authorities recommend that we keep using this vaccine." (UC Berkeley)

ACIP considered the available data on brain damage in 1991, and concluded that "Subsequent studies have failed to provide evidence to support a causal relation between DTP vaccination and either serious acute neurologic illness or permanent neurologic injury." It further noted that "The risk estimate from the NCES study of 1:330,000 for brain damage should no longer be considered valid on the basis of continuing analysis of the NCES and other studies." (Staff, Diptheria, tetanus, and pertussis: recommendations for vaccine use and other preventive measures, in Recommendations of the Advisory Committee on Immunization Practices (ACIP). Aug 8, 1991, CDC: Atlanta. p. 1-21.)

Known and non-controversial (i.e. everyone agrees that they occur) side effects of DTP vaccine include redness and tenderness at the injection site, fever, drowsiness, fretfulness, vomiting, and convulsions. (A vaccine information pamphlet from Kaiser gave the frequency as being 1 in 100 to 1 in 1000 for crying without stopping for three hours or longer, a temperature of 105 F or greater, or an unusual, high-pitched cry, and 1 in 1,750 for convulsions, generally from high fever, or shock collapse. I didn't see any frequencies in the PDR, other than describing these side effects as rare.) It is a good idea to give acetaminophen to children being vaccinated for pertussis, to reduce the chance of fever and febrile convulsions.

From Mike Dedek:

*************************************************************************
American Journal of Diseases of Children 1992; 146: 173-176, February 1992, 
"Pertussis outbreaks in Groups Claiming Religious Exemptions to Vaccinations", 
Etkind, Lett, et. al.:

2% non-vaccinated students are monitored>
:
 Key measures in preventing pertussis are immunization and judicious use of
 prophylactic antibiotics.  Pertussis can be prevented in children by
 immunization.  Unfortunately, controversy over the safety of the pertussis
 vaccine has reduced acceptance.  Highly publicized accounts of reactions to the
 vaccine and a dramatic increase in the number of malpractice lawsuits have made
 physicians and parents wary of using the diphtheria-tetanus toxoid and pertussis
 vaccine. {n4-n6} This publicity may have caused overinterpretation of the
 guidelines for medical contraindications. {n7} However, this overinterpretation
 creates its own risk for malpractice if a child given an inappropriate medical
 contraindication suffers damage due to disease.
*************************************************************************

This claim is examined at length by Lon Morgan, DC,DABCO in his Web site "A summary of JAPAN, SIDS, and PERTUSSIS IMMUNIZATION" at http://fp1.cyberhighway.net/~lmorgan/fearmongers/japan_sids.htm. It turns out that what went away, in 1975, when Japan increased the age at which it administered the first dose of the vaccine from three months to two years, was *claims of vaccine injuries* for SIDS. Japan had a compensation system for vaccine injuries, in which claims were to be paid unless other causes were clearly provable. Under this system, 11 claims were paid for what was termed Sudden Death, between 1970-1975 (this out of 25-30 million doses of pertussis vaccine). After the vaccination age was raised, no further claims were paid for Sudden Death related to vaccination. Since SIDS occurs before 12 months of age, any cases of SIDS can not be attributed to a vaccine which is given starting at 24 months.

Japan has, however, kept statistics for SIDS, and these statistics showed the numbers of SIDS cases *increasing*, rather than decreasing, at the time that the age of the first pertussis vaccination was raised. Though the delay in age for the first pertussis vaccination did not reduce the incidence of SIDS, it did result in a huge increase in pertussis cases, peaking at 13,105 cases and 41 deaths by 1979. For more details, and references, see Lon Morgan's site.

As a side note, recent vaccination rates for Japan, as listed in http://www.who.int/gpv-surv/country/japan.html, were, in 1996, 98% for polio, 100% for diptheria, pertussis, and tetanus, and 94% for measles; the coverage for BCG in 1993 was 91%.

Q3a.15 When is the DTP vaccine contraindicated?

Hypersensitivity to a vaccine component, including thimerosal, a mercury derivative. Defer vaccination in case of fever or acute infection (but not nececcarily for a mild cold without a fever). A history of convulsions is generally a contraindication to pertussis vaccination, but "The ACIP and AAP recognize certain circumstances in which children with stable central nervous system disorders, including well-controlled seizures or satisfactorily explained single seizures, may receive pertussis vaccine. The ACIP and AAP do not consider a family history of seizures to be a contraindication to pertussis vaccine." (PDR)

The following reactions to a previous dose are contraindications: An immediate anapylactic reaction. Encephalopathy occuring within 7 days following DTP vaccination. Precautions include a fever of >= 40.5 C (105 F) within 48 hours, collapse of shocklike state within 48 hours, persistent inconsolable crying for more than 3 hours within 48 hours, convulsions with or without fever within 3 days. (These latter are precautions rather than contraindications, because there might be circumstances, such as a pertussis epidemic, where you would still want to give the vaccine.)

Pertussis vaccine should not be given to anyone over seven years old (this may change, in time, with the new acellular vaccine, but further study is needed first).

Vaccine components capable of causing adverse reactions: for diptheria, thimerosal and toxoid; for tetanus, thimerosal and toxoid; for pertussis, bacterial components (Travel Medicine Advisor).

(Note: There is currently, as of 1999, a move toward replacing thimerosal in vaccines, so the reference to thimerosal here may shortly be out of date.)

Q3a.16 What are the advantages and disadvantages of the new acellular pertussis vaccine?

The big advantage is that the acellular vaccine has fewer side effects. The FDA initially held off on approving it for the earlier shots (while approving it for the fourth and fifth shots), mainly due to remaining uncertainty as to whether it is as effective as the whole cell vaccine. Reports from Japan indicated that it is, but a Swedish clinical trial indicated efficacy of 59% for one, and 64% for the other acellular vaccine. However, even this trial did show >90% efficacy against severe pertussis. (Shapiro) More recent results in Sweden and Italy indicate it is both safe and effective. On July 31, 1996, the FDA licensed one acellular pertussis vaccine for the inital three shots, and more followed. The American Association of Pediatrics has issued guidelines for the use of the new vaccine, which can be found at their web page, http://www.aap.org.

As of 7/14/95, results were available from two large European studies, involving 9,829 infants in Sweden and 15,601 infants in Italy. The National Institute of Allergy and Infectious Disease (in the US) reported that "three similar experimental vaccines effectively immunized 84% to 85% of the children in the trials, while resulting in fewer side effects than current, widely used versions." (Wall Street Journal, 7/14/95, p. A7A) A surprising result of the studies was that whole cell pertussis vaccine efficacy rates were lower than usual: "conventional vaccines provided protection for just 36% of children in Italy and 48% in Sweden. In the US the conventional vaccine proves effective in 70% to 95% of the children who are vaccinated." Officials suggested that infants in these studies might have had a higher intensity of exposure to the bacteria due to the lack of widespread vaccination in those countries, and that might explain the lower efficacy. A fourth acellular vaccine provided protection in 58% of the cases. The high efficacy and low side effects shown for the acellular pertussis vaccine in these studies will likely lead to requests that the FDA also approve the acellular vaccine for the earlier pertusis shots. More information on recent study results can be found in NEJM, Vol. 333, Number 16, Oct. 19, 1995 (B. Trollfors and others).

From Mike Dedek:

This next one indicates there's a better vaccine that may soon become
available [Note: this vaccine is now available, and recommended for
all doses in the US and some industrialized countries]:

*************************************************************************
In Pediatrics 1992; 89; 882-887, May 1992, "Acellular Pertussis Vaccination
of 2-Month Old Infants in the United States", Pichichero, Francis, et. at.:

ABSTRACT: This is the first study in children from the United States that
evaluates the immunogenicity of and adverse reactions to the Connaught/Biken
two-component acellular  pertussis  vaccine compared with whole-cell  pertussis
vaccine when given as a primary immunization series at 2, 4, and 6 months of
age.  Three hundred eighty infants were studied; 285 received acellular
diphtheria-tetanus toxoids- pertussis  (DTP (ADTP)) and 95 received whole-cell
DTP (WDTP).  Following the third dose, ADTP vaccination produced higher antibody
responses than WDTP to lymphocytosis-promoting factor (enzyme-linked
immunosorbent assay IgG geometric mean titer (GMT) = 131 vs 9 and Chinese
hamster ovary cell assay GMT = 273 vs 16) and to filamentous hemagglutinin (IgG
GMT = 73 vs 10) (all P < .0001).  Agglutinin responses were higher in WDTP
compared with ADTP recipients (GMT = 50 vs 37; P = .02).  Local reactions were
fewer for all three doses following ADTP vaccination.  Fever, irritability,
drowsiness, anorexia, vomiting, and unusual crying all occurred less frequently
in ADTP compared with WDTP recipients for one or more of the three doses.  We
conclude that this two-component ADTP vaccine when given as a primary series
produces greater immunogenicity and fewer adverse effects than the currently
licensed WDTP vaccine.

...A large case-control study
in Britain (National Childhood Encephalopathy Study) estimated that permanent
neurologic deficits may occur after its administration in 1 in 310000 doses
of WDTP.  However, a reanalysis of this and similar studies recently has led 
to the widely held conclusion that a causal association between WDTP vaccination
and permanent brain damage has not been demonstrated....

*************************************************************************
Public Health Rep 1992; 107: 365-366, May 1992/June 1992, "FDA Approves New
Whooping Cough Vaccine"

    The Food and Drug Administration (FDA) has licensed a  new  whooping cough
 vaccine  that may cause fewer side effects in children.

    The  new vaccine  is being approved at this time only for the fourth and
 fifth shots.  The current vaccine will continue to be used for the first three
 shots.  Additional research has been undertaken to ascertain whether it will be
 effective for preventing  pertussis  when used for primary inmunization -- the
 first three shots -- in infants.

   The  new vaccine  is acellular, meaning that it is made from only part of the
 pertussis  organism, as opposed to the whole organism from which the current
 vaccine is derived.

   Whooping cough ( pertussis)  is a highly contagious disease.  As many as 90
 percent of nonimmune household contacts acquire the infection.  Since routine
 immunization against  pertussis  became common in the United States, the number
 of reported cases of disease and deaths from it has declined from about 120,000
 cases with 1,100 deaths in 1950 to an annual average in recent years of about
 3,500 cases with 10 fatalities.

   The  new vaccine  appears to be as effective in older children as the current
 vaccine and to cause fewer adverse reactions.  It has been widely used in Japan
 -- where it was developed -- with apparent success in children older than 2
 years.  It will be combined with diphtheria and tetanus toxoids (DTP) and sold
 under the brand name Acel-Imune.

   Gerald Quinnan, MD, acting director of FDA's Center for Biologics, where the
 vaccine was evaluated and licensed, said that the availability of an acellular
 vaccine is a significant step forward in infectious disease control.

  The most common adverse reactions seen in clinical trials of the acellular
 pertussis  vaccine included tenderness, redness, and swelling at the injection
 site, fever, drowsiness, fretfulness, and vomiting.

  The  new pertussis vaccine  component is produced by Takeda Chemical
 Industries Ltd. of Osaka, Japan, and is combined with diphtheria and tetanus
 toxoids manufactured by Lederle Laboratories of Wayne, NJ.  Lederle will also
 distribute the product in the United States.  The vaccine is administered by
 injection.

  The approval of the  new vaccine  comes at a time when the Federal Government
is emphasizing early childhood immunizations in the wake of the largest reported
measles outbreak in the nation in 20 years -- with more than 27,600 cases and 89
deaths reported in 1990.

  The aim is to reach a goal of full immunization for 90 percent of children by
 the time they are 2 years old.
*************************************************************************

Despite the acellular vaccine's comparable efficacy and few adverse reactions, the whole cell pertussis vaccine retains one advantage which ensures some continued use. It is cheaper, and more organizations know how to make it In developing countries, where pertussis is a major killer, and money for vaccines in short supply, it is not clear that the advantages of the acellular vaccine justify the additional cost.

Q3a.17 What are some of the risks of the DT (diptheria and tetanus) vaccine?

Most of the risk in the DTP vaccine comes from its pertussis component; the diptheria and tetanus vaccines are quite safe. Reactions to the diptheria vaccine are quite rare. Most reactions are local, limited to swelling at the injection site. The same is true of the tetanus shot. "Severe local reactions can occur if too many shots are received; this phenomenon was frequently seen in military recruits who received unneeded immunizations." (Pantell, Fries, and Vickery)

Q3a.18 When is the DT vaccine contraindicated?

Should be avoided during the first trimester of pregnancy. People who have had a reaction (which is very rare) should avoid it.

Vaccine components capable of causing adverse reactions: for diptheria, thimerosal and toxoid; for tetanus, thimerosal and toxoid (Travel Medicine Advisor).

(Note: There is currently, as of 1999, a move toward replacing thimerosal in vaccines, so the reference to thimerosal here may shortly be out of date.)

Q3a.19 Under what circumstances is tetanus toxoid given to pregnant women?

Tetanus toxoid is given to pregnant women in countries where there is a high risk of neonatal tetanus (due to factors which enhance the risk of cord contamination in these countries).

===============================================================================
Section 3b. Polio
[This section last updated September 19, 1999.]

Q3b.1 What is polio, and what are the risks of the disease?

Polio is a contagious viral disease which crippled tens of thousands in the 1950s, and killed more than a thousand a year. Because it is a mild gastrointestinal illness in young children and a serious paralytic illness in older people, it had an unusual epidemiology, with more cases of paralytic polio turning up in wealthy areas and as sanitation improved. 80-90% of cases of polio are the minor illness; the rest are paralytic poliomyelitis. In paralytic poliomyelitis, < 25% suffer permanent severe disability, about 25% have mild disabilities, and > 50% recover with no residual paralysis. Mortality is 1 to 4%. "Recently, a post poliomyelitis syndrome has been described, characterized by muscle fatigue and decreased endurance... The syndrome occurs many years after an attack of paralytic poliomyelitis..." (Merck).

Q3b.2 How effective is the polio vaccine?

The Merck Manual and the Physician's Desk Reference give its effectiveness as 95%. An article in a WHO publication (Hull and Ward) estimates effectiveness at 80%. (As with other WHO estimates, the lower effectiveness rating reflects an estimate of effectiveness in the field in a variety of countries, including countries in the Third World. Polio vaccine effectiveness can deteriorate if it is exposed to too much heat, which can happen in vaccination programs in some countries.)

Q3b.3 How long does the polio vaccine last?

It provides lifelong immunity.

Q3b.4 What is the difference between oral polio vaccine (OPV) and inactivated polio vaccine (IPV)?

Oral polio vaccine provides better immunity, and was until recently usually the recommended form, "because induces intestinal immunity, is simple to administer, is well accepted by patients, results in immunization of some contacts of vaccinated persons, and has a record of having essentially eliminated disease associated with wild poliovirus in this country." (PDR) However, it carries a small risk of paralysis (see the answer to the next question for details).

Recently, with increased progress in worldwide eradication of polio, both ACIP and AAP have changed their recommendation to IPV for all shots. OPV remains the vaccine of choice for countries where polio is still endemic, and for people who will be shortly travelling to such countries.

Q3b.5 I've heard that it is possible to contract polio from handling the diapers of recently immunized infants. How long after receiving the vaccine does the child's excrement continue to contain the virus?

*************************************************************************
From Caren Feldman:

> Speaking of this, I know there has been mention in the past of contracting
> polio from handling diapers of recently immunized infants.  Does anyone
> know how long after receiving the vaccine the child's excrement continues to
> contain the virus?  The reason I ask is because sean got his polio booster
> and Rachel has only received the first vaccine in the series.  The doctor's
> office said she wain no danger of contracting poliofrom him since they don't
> come in contact with each other *that* closely.  However, I have to be extra
> careful after helping Sean clean up (he needs help sometimes) or handling his
> underwear to make sure I wash my hands thoroughly.  So, how long until I
> can stop being paranoid about remembering to wash my hands after handling
> the laundry?  (I forgot to ask)
> 
The short answer is 6 weeks. But since you brought up the subject...here's what
I fond out about polio immunizations:

When I had read one poster's response that the live polio virus from feces
was actually weakened virus that would in fact help immunize unimmunized kids
they'd come in contact with it, naturally I didn't believe it. Well, not at
first. But I had enough doubts of my disbelief to start asking around, and came
up with some (at least to me) little known facts about polio and polio
immunizations. I am presenting it to misc.kids for everyone's edification.

Indeed, live virus from a recently immunized child's feces is weakened virus
that health officials actually hope unimmunized kids  come in contact with to
provide them with individual immunity and the general population with "herd"
immunity.

Now here's the tricky part. One of the attenuated strains used to make the
vaccine has a very low but existing back mutation rate, back to the "wild
type", i.e. back to "regular" polio. If the weakened virus the child has been
given mutates back to wild-type polio, any adult with no immunity to it (or
an immunized adult for whom the immunization series did not "take") is
potentially at risk for full blown polio. Of course, people with weak immune
systems may be at risk even from  weakened virus. Steroid use may also cause
the immune system to weaken (besides the usual anti-rejection drugs, HIV,
leukemia) and thus increase susceptibility for contracting the virus.

Polio in young children manifests itself as a mild gastrointestinal ailment.
Polio in older children and adults starts as a mild gastroenteritis but with
complications that may lead to paralysis. Before the advent of improved public
sanitation, most young children were exposed to and probably contracted the
polio virus, so by adulthood, chances were everyone had immunity to it. It
was only when public sanitation improved to where exposure to the virus was
delayed until later childhood that polio epidemics became prevelant. Polio
outbreaks in the US were less frequent among poor children than among more 
affluent families.

The CDC estimates the chances of getting polio from a first immunization (I
presume this means gastroenteritis symptoms in babies, not paralytic polio)
is one in half million. The chances of getting polio from subsequent
immunizations is 1 in 12 million. I assume the chances of secondarily
contracting polio from feces are even rarer.

These rare cases probably account for the supermarket tabloid (not to mention
"60 Minutes") stories of adults catching polio from recently immunized kids
who'd been given oral vaccine. For those in the US, you will be glad to
hear that a federal compensation program exists, called the National Vaccine
Injury Compensation Program, to help those stricken with paralytic polio as a
result of coming into contact with a recipient of the oral polio vaccine.


Thanks go to two posters on sci.med for answering my questions regarding this
subject.
*************************************************************************

Q3b.6 What are some other risks of the polio vaccine?

A small risk of anaphylactic shock.

Q3b.7 When is the polio vaccine contraindicated?

Because of the small risk of paralytic polio in recipients and contact of recipients of OPV, it should not be given to anyone who is immune-compromised or who has immune-compromised family members. (The PDR has a really long list of immune deficiencies involved, which you can check if you think anyone in your family falls in this category.) In these cases, IPV should be given instead. IPV is also recommended for adults who are at risk for polio (such as unvaccinated adults travelling to an area where polio is endemic). Both vaccines are contraindicated for people with an anaphylactic allergy to neomycin or streptomycin.

Vaccine components capable of causing adverse reactions: for both OPV and IPV, streptomycin, neomycin, and phenol red; for IPV, animal protein, formaldehyde, and polymyxin B (Travel Medicine Advisor).

Q3b.8 Isn't it true that wild polio has been eliminated in the US?

From Mike Dedek:

*************************************************************************
>From The Reuter Library Report, 2/26/93, "U.N. Warns on need for Polio 
Immunisation" copyright 1993 Reuters:

 The last  outbreak of polio  took place in the Netherlands 15 years ago. The
 virus was carried to Canada and the United States by infected people visiting
 their relatives, the WHO said. This caused the United States' last  polio
  outbreak  which hit the Amish community in the state of Pennsylvania in 1979.

*************************************************************************
>From The [London] Independent, 2/9/93, pg. 12, "Why child vaccines may be a
shot in the dark", by Tessa Thomas:

 After numerous  cases  in which the ''live'' oral  polio  vaccination was
 found to have caused the disease, the American government is considering
 reintroducing the inactivated injectable version. In the UK, the Department of
 Health advocates the live version on the basis that it deactivates any wild
 polio  virus that reaches the gut, preventing it being excreted into the
 community, thus conferring community protection. The injectable vaccine acts
 only on the bloodstream, protecting the individual but not breaking the chain of
 infection. Lobbying by the Association of Parents of Vaccine Damaged Children
 has prompted an acknowledgement by Virginia Bottomley, the Secretary of State
 for Health, that the live vaccine is responsible for 50 per cent of recent new
 cases of polio.  Between 1978 and 1991 there were 42  cases of polio,  18 of
 which followed vaccination and nine of which followed infection through contact
 with the vaccinated child.

*************************************************************************
The Atlanta Journal and Constitution, 12/19/92, "Cases in Netherlands put
Americas at risk for polio", by Steve Sternberg, Section E; pg. 1

  The last polio case in the Americas emerged on Aug. 23, 1991 in the remote
  Peruvian highlands village of Pichinaki...

*************************************************************************
UPI 12/10/92:

  Except for a few rare vaccine-associated  cases,  there have been no  cases
  of polio  in the United States since 1986 when there was one imported  case.
  The current vaccine, Sutter said, is close to 100 percent effective in
  preventing the disease.

*************************************************************************

Q3b.9 Why are we still vaccinating for polio, then?

The AAP and ACIP continue to recommend vaccination for polio for several reasons. First, the risk of the disease is much higher than the risk of the vaccine. Second, though there is no wild polio in the US *now*, with high levels of vaccination, there is still polio elsewhere in the world. 148,000 cases were reported to WHO in 1990. China reported 5,065 cases. The USSR reported 337 cases. India reported 7,340. (Hull and Ward) There have been several outbreaks of polio in countries 2 or more years after the last reported case of polio. Importation from polio endemic countries has led to outbreaks in Oman (1988-89 and 1993), Jordan (1991-92), Malaysia (1992), and the Netherlands (1992-93) (MMWR, reported in HICNet Medical News on 15 August 1994). Wild poliovirus type 3 was isolated during January-February 1993 among members of a religious community objecting to vaccination in Canada (although no actual cases of parlytic polio occurred in Canada at this time). There is a concern that if levels of vaccination were reduced in the US, polio could be reintroduced, and we could see polio epidemics here again.

Encouraged by the worldwide elimination of smallpox, WHO, in 1988, set a goal of eradicating polio from the world by 2000. Since then, the number of cases in the world has declined dramatically (29,916 in 1989 and 16,435 in 1990), and the number of countries reporting 0 cases has increased (74 countries in 1985 and 116 countries in 1990). As of 1993, the number of cases worldwide has falled to 9714, and nearly 70 percent of all countries reported no cases. (Progress toward global eradication of poliomyelitis, 1988-1993. MMWR 1994 Jul 15; 43:499-503. Summarized in Journal Watch Summaries for July 22, 1994.) As of 1999, WHO reports still further progress, "In 1988, virus circulated widely on all continents except Australia. By 1998, the Americas were polio-free (certification of eradication in 1994), transmission has been interrupted in the Western Pacific Region of WHO, including China, and in the European Region, except for a small focus in south-east Turkey. As shown below, only three major foci of transmission remain: South Asia (Afghanistan, Pakistan, India), West Africa (mainly Nigeria) and Central Africa (mainly Democratic Republic of Congo)." So another factor in the decision to continue vaccinating for polio is the hope that it can be eliminated for good.

After much debate, the US has switched to IPV instead of OPV (IPV being less effective, but lower in side effects). The decision at first was to continue with OPV because it has been so successful, the rate of side effects is still considered very low, and because of various advantages in producing immunity (see above). According to the 1993 PDR, "The choice of OPV as the preferred poliovirus vaccine for primary administration to children in the United States has been made by the ACIP, the Committee on Infectious Diseases of the American Academy of Pediatrics, and a special expert committee of the Institute of Medicine, National Academy of Sciences." In 1995, though, that decision was changed, and the injected vaccine became recommended for the first two polio shots. As progress toward worldwide polio eradication continued, and as the change in the vaccination schedule (from an oral to an injected form) did not result in any decline in vaccination coverage, ACIP and AAP are now recommending IPV for all shots.

===============================================================================
Section 3c. MMR (measles, mumps, and rubella)
[This section last updated on October 23, 1999.]

Q3c.1 What is measles, and what are the risks of the disease?

Measles is one of the most contagious infectious diseases. "A child can catch measles by breathing the air in a doctor's waiting room two hours after an infected child has left." (Fettner) 90% of susceptible household contacts get the disease (Harrison). Measles spreads very rapidly in unexposed populations. In 1951, it was introduced to Greenland by a recently arriaved visitor who went to a dance as he was coming down with it, and in three months it spread to more than 4000 cases and 72 deaths. The attack rate was 999 cases per 1000 people. In 1875, measles was introduced to Fiji and killed 30 percent of the population (Smith).

In areas where it was endemic, before the measles vaccine, measles epidemics used to occur at regular intervals of two to three years, usually in the spring, with small local outbreaks in intervening years. Mortality is low in healthy, well-nourished children unless complications ensue (Merck), but nevertheless there were 400 deaths a year before an improved measles vaccine was introduced in 1966 (Pantell, Fries, and Vickery). Complications include brain infection, pneumonia, convulsions, blindness, various bacterial infections, encephalitis, and SSPE (a fatal complication which can occur years after a person has had measles). Pregnant women who get measles have a 20% chance of miscarriage.

Worldwide, measles is one of the leading causes of childhood mortality. "Measles has been called the greatest killer of children in history." (Clements, Strassburg, Cutts, and Torel) In 1990, "45 million cases and around 1 million deaths were estimated to occur in developing countries. Thus measles is still responsible for more deaths than any other EPI target diseases. The true number dying as a result of measles may be twice the estimated 1 million if the recently documented delayed effect of the disease is taken into account." (Ibid.) Mortality is higher in developing countries due to a difference in the age at which most people catch it (measles is a more dangerous disease in the very young), poorer nutrition, less availability of treatment for bacterial chest infections, and other environmental factors. However, "Even in countries with adequate health care and healthy child populations, the complication rate can reach 10%." (Ibid.)

More information on the incidence of measles complications is found in the answer to Q3c.2.

Q3c.2 How common was measles before routine vaccination, and how common is it now?

*************************************************************************
From Anthony C.:

I havent finished reading this thread so pardon if someone else has
already posted this information

Rates of complications of measles and measles immunization
			Measles per 10^5 Vaccine per 10^5
Encephalomylelitis	50-400		.1
sspe			.5-2.0		.05-.1
Pneumonia		3800-1000	
Seizures		500-1000	.02-19
Deaths			10-10000	.01

These statistics are worldwide, hence the variablility in numbers.  The
higher rates of pneumonia and death represent figures collected from
India, Nambia, Nigeria, bangladesh and other countries with developing
health care industries.

As far as the number of people afflicted with measles in the US
	Cases		Deaths
1963	385,566		364 	Inactivated measles type vaccine available
1964	458,093		421
1966	204,136		261	public health administration of vaccine
1967	62,705		81
1968	22,231		24
.
.hovers around 20-70,000
.
1977	57,345		15
1978	26,871		11
1979	13,597		6
1980	13,506		11
1981	3,032		2
1982	1,697		2
1983	1,497		4
1984	2,587		1
1985	2,822		4
1986	6,273		2
1987	3,588 		2
1988	2,933		not available
1989	16,236		41
1990	26,520		97

iMajor foci of retransmission barring the complete elimination of measles:
1) unimmunized indigent, inner city youngsters.
2) illegal aliens.

I hope this is useful.  My source is Zinsser microbiology, 20th edition
pages 1013-1015, joklik et al.
*************************************************************************

Q3c.3 How effective is the measles vaccine?

The Merck Manual and the Physician's Desk Reference estimate its effectiveness at 95%. This estimate is based on studies of the immunity induced by a series of vaccinations beginning at 15 months. Another article, estimating the immunity induced in field conditions (including some Third World countries, which may have less reliable vaccine storage) by a series of injections beginning at 9 months (the injections are started earlier in areas where measles is widespread), estimated effectiveness as 85% (Clements, Strassburg, Cutts, and Torel).

A recent article in Pediatric News (Imperio. Vaccine-Exempt At Higher Risk For Measles. Pediatric News 33(9):9, 1999.) reported that "Individuals aged 5-19 years who were not vaccinated due to religious or philosophical exemptions were, on average, 35 times more likely than vaccinated individuals to contract measles, according to a population-based, retrospective cohort study."

Q3c.4 How long does the measles vaccine last?

The Merck Manual describes it as "durable." The PDR says that all of the antibody levels induced by MMR have been shown to last up to 11 years without substantial decline, and "continued surveillance will be necessary to determine further duration of antibody persistance."

Q3c.5 What are some of the risks of the measles vaccine?

There is a small chance of complications similar to the complications of measles (pneumonia, encephalitis, SSPE). Information on the frequency of these complications is included in the answer to Q3c.2. There is some risk of anaphylaxis. This risk is low; from the time that VAERS was instituted in 1990 till the publication of Update: Vaccine Side Effects, Adverse Reactions, Contraindications, and Precautions by ACIP in 1996, >70 million doses of MMR vaccine had been distributed in the US, and only 33 cases of anaphylactic reactions had been reported to VAERS. It has been traditionally believed that this risk is mainly for people allergic to eggs or neomycin. However, recent studies indicate that anaphylactic reactions are not associated with egg allergies, but with some other component of the vaccine. There have been some case reports, in the US and Japan, of anaphylactic reactions to the MMR vaccine in people with an anaphylactic sensitivity to gelatin.

In rare instances, MMR vaccine can cause clinically apparent thrombocytopenia within 2 months after vaccination. Passive surveillance systems report an incidence of 1 case per 100,000 doses in Canada and France, and 1 per million in the US. Prospective studies have reported a range from 1 in 30,000 in Finland and Great Britain to 1 in 40,000 in the US, with a clustering of cases about 2-3 weeks after vaccination.

An article in the Feb 28, 1998 Lancet (based on 12 cases) about a possible association between inflammatory bowel disease, autism, and MMR vaccine (Wakefield et al) raised concerns that the vaccine might increase the risk of autism. Wakefield and his colleagues did not claim to have actually shown that the vaccine caused autism, but rather called for further investigation of the question. An accompanying editorial in the same issue of Lancet expressed concerns about the validity of the study.

The article, and the public concern it raised, led to several further investigations of whether such an association existed. A research letter in the May 2, 1998 issue of Lancet reported on a 14-year prospective study, in Finland, of children who had experienced gastrointestinal symptoms after receiving the MMR vaccine. 31 children (out of 3 million vaccine doses) reported gastrointestinal symptoms; all recovered, and none developed autism. A Working Party on MMR Vaccine of the United Kingdom’s Committee on Safety of Medicines (1999) examined hundreds of reports, collected by lawyers, of autism or Crohn's disease (a gastrointestinal disease) and similar problems, after the MMR vaccine, and concluded that there was no causal relationship. A Swedish study (Gillberg and Heijbel 1998) found no difference in the prevalence of autism in children born before the introduction of MMR vaccine in Sweden, and children born after. Wakefield and colleagues did laboratory assays in patients with inflammatory bowel disease (the mechanism which they had proposed for autism following the MMR vaccine), and found them negative for measles virus (Chadwick 1998, Duclos 1998, cited by the CDC at http://www.cdc.gov/nip/vacsafe/vaccinesafety/sideeffects/autism.htm).

Finally, a study in the June 12, 1999 issue of Lancet examined children born with autism since 1979 in eight North Thames health districts, to look for changes in incidence or age at diagnosis since the introduction of MMR vaccination in the UK in 1988. The study found a steady increase in cases of autism, with no sudden change in the trend after the introduction of the MMR vaccine. Parents most frequently reported first noticing symptoms of autism at around the age of 18 months, after the MMR vaccine would have been received, but there was no difference in age at diagnosis between those vaccinated before and after 18 months and those never vaccinated. Developmental regression (which occurred in about a third of the cases of autism) was not clustered in the months after vaccination.

Q3c.6 What is mumps, and what are the risks of the disease?

Mumps is a viral disease which is less contagious than measles or chicken pox. It causes swollen salivary glands. The most common complication is swelling of the testes (in about 20 percent of males post puberty) and, less commonly, ovaries. Rarely, it can lead to sterility. Other complications are meningitis (less common than in measles) and acute pancreatitits. (A much longer list of complications can be found in the Merck Manual.)

Q3c.7 How common was mumps before routine vaccination, and how common is it now?

105,00 cases were reported in 1970; by 1990 the rate of reported cases was down to 5,300.

Q3c.8 How effective is the mumps vaccine?

The Merck Manual estimates its effectiveness at 95%. The Physician's Desk Reference gives its effectiveness as 96%. Switzerland has gotten lower efficacy rates, for mumps, out of its strain of the MMR vaccine, and Swiss scientists have been comparing the efficacy of different strains to improve this situation (Swiss Medical Weekly, http://www.smw.ch/archive/1997/127-26-360-96.html and http://www.smw.ch/archive/1998/128-17-351-98.html).

Q3c.9 How long does the mumps vaccine last?

The Merck Manual describes it as "durable." "Mumps immunization provides protection through the blood serum antibodies for at least 12 years, and possibly much longer." (Pantell, Fries, and Vickery) (See also Q3c.4 for the PDR's description of the duration of all the MMR-induced antibodies.)

Q3c.10 What are some of the risks of the mumps vaccine?

"Rarely, side effects of mumps vaccination have been reported, including encephalitis, seizures, nerve deafness, parotits, purpura, rash, and prurittis." (Merck. Encephalitis and convulsions were also on Merck's list of complications for mumps itself.) According to ACIP's 1996 report on vaccine adverse reactions, "Aseptic meningitis has been epidemiologically associated with receipt of the vaccine containing the Urabe strain of mumps virus, but not with the vaccine containing the Jeryl Lynn strain, the latter of which is used in vaccine distributed in the United States." [MMWR 45(No. RR-12), 1996]

Q3c.11 What is rubella, and what are the risks of the disease?

Rubella is a mild illness, consisting of a mild fever and rash. Rare complications include ear infections and encephalitis, but the real danger is to pregnant women. During the last rubella epidemic, in 1964, 20,000 children were born with birth defects caused by rubella. Birth defects include deafness, cataracts, microcephaly, and mental retardation. Children born with congenital rubella are als susceptible to rubella panencephalitis in their early teens.

Q3c.12 How common was rubella before routine vaccination, and how common is it now?

Before the development of the rubella vaccine, epidemics used to occur at irregular intervals in the spring, with major epidemics at 6 to 9 year intervals. (This means that one was just about due when the vaccine came out in 1969.) There have been no major epidemics since 1969, but the number of cases of rubella and congenital rubella syndrome increased starting in 1989 (Merck, also California Morbidity for November 19, 1993). (It was still a small fraction of the pre-vaccine number, though, see table of disease frequencies in section 1.) "Serological surveys conducted in the late 1970s and the 1980s indicated that 10 to 25 percent of United States women of child-bearing age were shown to be susceptible to rubella." (California Morbidity, November 19, 1993) It now appears to be declining again: "Following a resurgence of rubella and congenital rubella syndrome (CRS) during 1989-1991, the reported number of rubella cases during 1992 and 1993 was the lowest ever recorded." (MMWR, cited in June 9, 1994 HICNet Medical News Digest.)

Q3c.13 How effective is the rubella vaccine?

The Merck Manual estimates its effectiveness at 95%. The Physician's Desk Reference gives its effectiveness as 99%.

Q3c.14 How long does the rubella vaccine last?

The Merck Manual describes it as "sustained." (See also Q3c.4 for the PDR's description of the duration of all the MMR-induced antibodies.)

Another reference, from Heather Madrone:

*************************************************************************
D. M. Horstmann "Controlling Rubella:  Problems and Perspectives"
_Annals of Internal Medicine_, vol. 83, no. 3, pg. 412

Horstmann found reduced antibody formation 3-5 years after administering
the vaccine and 25% of those tested showed no immunity to rubella at
all.
*************************************************************************

Q3c.16 What are some of the risks of the rubella vaccine?

The PDR has a long list of possible adverse reactions (besides arthritis and arthralgia, usually short-lived, see above). Most of them are either mild or rare.

Q3c.17 When is the MMR vaccine contraindicated?

People with an anaphylactic or anaphylactoid allergy to eggs or neomycin should not get the vaccine. Other allergies or chicken or feather allergies are not a contraindication. Vaccination should be deferred in case of fever. The PDR give active untreated tuberculosis as a contraindication, but the AHFS says that there is no evidence of a need to worry about TB. Both give immune deficiency as a contraindication (see PDR for a long list of immune deficiencies involved). Immune globulin preparation or blood/blood product received in the preceding 3 months. The same contraindications apply individually to measles and mumps vaccines, but the rubella vaccine can be given by itself to people with an anaphylactic egg allergy. The other contraindications still apply to the rubella vaccine alone. (California Morbidity, October 31, 1987)

Vaccine components capable of causing adverse reactions: for mumps and measles, chick fibroblast components; for mump, measles, and rubella, neomycin (Travel Medicine Advisor).

===============================================================================
Section 3d. HiB (Hemophilus influenze B)
[This section last updated September 19, 1999.]

Q3d.1 What is hemophilus influenze B, and what are the risks of the disease?

HiB is a bacteria which is one of the leading causes of meningitis in young children. About 60% of cases are meningitis. The remaining 40% are cellulitis, epiglottis, pericarditis, pneumonia, sepsis, and septic arthritis. Mortality rate can be about 5%, and there are neurologic sequelae in up to 38% of survivors.

Q3d.2 How common was HiB before routine vaccination, and how common is it now?

Before routine vaccination, about 12,000 cases a year in the US, with a cumulative risk of 1 in 200 that a child would get the disease by age 5. A vaccine was introduced in 1985. Since the introduction of the Hib conjugate vaccine in 1988, the race-adjusted incidence of Hib among children less than 5, has declined from 41 cases per 100,000 in 1987 to two cases per 100,000 in 1993. (The incidence for people five or older remained stable. Hib is most serious in children under 5.) (A decline of 95%, despite the fact that the National Health Interview Survey showed only 67% of children 12-23 months had received at least one dose, and 36% three or more doses. This decline is attributed to the elimination of carriage, which reduces Hib exposure even in unvaccinated children.) The CDC set a goal of eliminating Hib in the US by 1996. (HICN708 Medical News, "[MMWR] Progress Elimination Haemophilus influenzae type b") As of September 1999, this goal wasn't met, but there has been a significant decline; MMWR's "TABLE III. Provisional cases of selected notifiable diseases preventable by vaccination, United States week ending September 11, 1999" records a cumulative total for 1998 of 788 cases, and for 1999 of 820 cases, in the US.

Q3d.3 How effective is the HiB vaccine?

Estimates from different labs vary a lot. AHFS Drug Information, after noting this variability, and the uncertainty as to what antibody level is adequate for protection, says that in one study, 75% of children 18-23 months and 85% of children 24-29 months had serum anticapsular antibody levels of one microgram per milliliter or greater. The PDR lists numerous studies, with results ranging from 100% efficacy to one study in which vaccinated children had more cases of HiB than the unvaccinated group. With the exception of the latter study, all of the studies showed significant positive results, often with efficacy estimates over 90%.

According to a NY Times article of 12/18/90, HiB vaccine produces lower antibody response among Native Americans, but the new conjugated vaccine seems to produce higher antibody response in Native American children and may protect all children at a younger age.

Q3d.4 How long does the HiB vaccine last?

The duration of immunity is unknown. However, the disease is only dangerous to very small children.

Q3d.5 What are some of the risks of the HiB vaccine?

In a study of 401 infants, fever occurred in 2%, and redness, warmth, or swelling in 3.3%. All adverse reactions were infrequent and transient. (PDR) The Institute of Medicine reported in 1994 that evidence favored rejection of a causal relationship between early onset HiB disease and conjugate vaccines, but favored acceptance of a causal relationship between early onset disease in children 18 months old or more whose first vaccination was with unconjugated PRP vaccine. [MMWR 45(No. RR-12), 1996]

Q3d.6 When is the HiB vaccine contraindicated?

Hypersensitivity to any component of the vaccine, including diptheria toxoid and thimerosal in the multi-dose presentation.

Vaccine components capable of causing adverse reactions: phenol, bacterial polysaccharides, thimerosal (Travel Medicine Advisor).

(Note: There is currently, as of 1999, a move toward replacing thimerosal in vaccines, so the reference to thimerosal here may shortly be out of date.)

Q3d.7 What about rifampin prophylaxis?

An alternative to HiB vaccination is rifampin prophylaxis, but it could be unwieldy to administer. AHFS Drug Information says that it is "effective for eradicating nasopharyngeal carriage of HiB, but the efficacy of the drug for prevention of secondary disease has not been firmly established."

===============================================================================
Section 3e. Hepatitis B gamma globulin and hepatitis B vaccine
[This section last updated on September 15, 1999.]

Q3e.1 What is hepatitis B, and what are the risks of the disease?

There are several forms of hepatitis, infections of the liver which cause jaundice, nausea, and weakness. Hepatitis B is spread mainly by contact with infected blood and by intimate contact with bodily fluids, such as in sexual intercourse and childbirth. However, the hepatitis B virus is far more resilient than, for example, the AIDS virus, and the disease is not strictly a venereal disease, and can be caught even by people who are not sexually active. Hepatitis B becomes chronic in 5-10% of those infected. Complications include hepatic necrosis, cirrhosis of the liver, chronic active hepatitis, and hepatocellular carcinoma. Hepatitis B is endemic throughout the world, and a serious problem in groups at increased risk. Information about hepatitis B is available by calling 1-800-HEP-B-873. Another source of information about hepatitis B and many other forms of liver disease is:

           American Liver Foundation
           1425 Pompton Avenue
           Cedar Grove, NJ  07009

	Hepatitis B Coalition
	1537 Selby Ave  #229
	St Paul, MN 55104
	(612) 647-9009

http://cpmcnet.columbia.edu/dept/gi/disliv.html

A US government source of information on hepatitis is:

	Hepatitis Branch
	Mailstop G37
	CDC
	Atlanta, GA 30333
	or call the CDC Automated Voice Information System at (404) 332-2553.

Q3e.2 How common is hepatitis B?

"The estimated lifetime risk of HBV infection in the United States varies from almost 100% for the highest risk groups to approximately 5% for the population as a whole." (PDR) The CDC estimates about 0.75 - 1 million chronic carriers in the US, and more than 170 million are estimated worldwide.

Q3e.3 What is hepatitis B gamma globulin, and when is it given?

It is given to people who have already been exposed to hepatitis B, to boost their immunity. In particular, it is given to children born to mothers with hepatitis B. It should be given as soon as possible after birth for the best results.

Q3e.4 How long does the immunity provided by hepatitis B gamma globulin last?

Two months, maybe longer.

Q3e.5 What are the risks and contraindications of hepatitis B gamma globulin?

No known contraindications. A couple of diseases (see PDR for more information) are listed under precautions (a weaker form of warning than contraindication - in the case of precautions gamma globulin may be given, but the extra risks of giving the gamma globulin have to be weighed against the benefits). These diseases, though, aren't ones a newborn is likely to have, so they would probably not apply in the case of giving it to the newborn of a mother infected with hepatitis B.

Q3e.6 How effective is the hepatitis B vaccine?

It varies depending on the age, sex, and general health of the recipient. About 96-100% in infants and children 19 and under, 94-99% in adults 20-39, 88-91% in adults 40 or older. May be lower in men than women. Lower (only 64% in one study) in hemodialysis patients. (AHFS Drug Information 1992) The PDR estimated 95-96% for infants, and agrees with AHFS about the conditions which reduce effectiveness.

Q3e.7 How long does the hepatitis B vaccine last?

There is evidence that immunity lasts up to ten years, but beyond that, the duration is uncertain, and the need for booster doses not defined. (My source for the duration is Journal Watch, 9/1/93.)

Q3e.8 What are some of the risks of the hepatitis B vaccine?

Hepatitis B has traditionally been considered one of the safest and least reactogenic vaccines:

"During clinical studies involving over 10,000 individuals distributed over all age groups, no serious adverse reactions attributable to vaccine administration were reported." (PDR, 1993) The most common adverse reactions were injection site soreness (22%) and fatigue (14%). A longer list of adverse reactions can be found in the PDR. "Update: Vaccine Side Effects, Adverse Reactions, Contraindications, and Precautions," published by ACIP in 1996, reported that VAERS data showed a low rate of anaphylaxis (approximately one event per 600,000 doses given).

More recently, controversy has been aroused by news reports, particularly in France, of new or reactivated cases of multiple sclerosis, and other demyelinating disorders, within two to three months following administration of hepatitis B vaccine. Critics argue that the risk is too high for a vaccine routinely given to children not directly at much risk for hepatitis B. Supporters of vaccination argue that, given the demonstrated risk of liver cancer and cirrhosis of the liver from hepatitis B, effective vaccination programs should not be abandoned for a hypothetical risk that the vaccine might in rare cases lead to multiple sclerosis and other demyelinating diseases.

As is the case in other controversies about vaccination risks, part of the difficulty is assessing just what effect the hepatitis B vaccine may have on demyelinating diseases. Multiple sclerosis is, in some countries, the most common neurological disease of young adulthood. Though most commonly reported between 20 and 40, it can be reported at younger and older ages, and, given near universal vaccination of pre-adolescents, some cases of MS are to be expected, simply by chance, in proximity to vaccination. Since the incidence of cases of multiple sclerosis attributed to the vaccine, in France and elsewhere, is less than the number already expected for the age range in question, statistical analysis is required, to determine whether the risk of MS and other demyelinating diseases is in fact higher in populations vaccinated for hepatitis B, and, if so, what the risk might be.

Several studies have been carried out, to date, to assess this risk, and more are ongoing.

ACIP reported, in 1996, that evidence was inadequate to establish or reject a causal relationship between hepatitis B vaccine and demyelinating diseases of the central nervous system.

The French National Drug Surveillance Committee studied people who received more than 60 million doses of hepatitis B vaccine between 1989 and 1997, and found that the prevalence of neurological disease, including MS, was actually lower in this group than in the general population.

Three French studies, prompted by reports of MS, showed a slightly increased relative risk in the vaccinated population, but not one which was statistically significant. In response to this, the French government required a risk-benefit analysis. The risk-benefit analysis did not attempt to determine whether the hepatitis B vaccine in fact causes MS or other demyelinating diseases, but rather to use the largest possible risks which could be derived from the studies which had been done, and weigh these against the expected benefits of hepatitis B vaccine (with both being assessed in a statistical, quantititive fashion). This study concluded that, though it isn't possible to determine yet whether there is an association between the hepatitis B vaccine and MS, the benefits of the vaccine for a given vaccinated pre-adolescent cohort would clearly outweigh the risks.

In Canada, the Alberta Ministry of Health reported that a preliminary examination of hospital admission data between 1975 and 1995 suggests that the introduction of the hepatitis B vaccine in the mid-1980s has not been marked by an increase in the incidence of multiple sclerosis.

The World Health Organization Viral Hepatitis Prevention Board (VHPB) assembled experts, on September 28-30, 1998, to review the epidemiology and current understanding of MS. This group examined data on the epidemiology of hepatitis B, the epidemiology of multiple sclerosis, from national reporting systems in the US, Italy, and Canada, from one active pediatric surveillance system in Canada, from industry post-marketing surveillance and clinical data, from published studies of hepatitis B safety, and from preliminary reports of a small number of unpublished epidemiological studies in the US, France, and the UK. They tried to decide between three hypotheses for explaining the relationship between the hepatitis B vaccine and MS: 1) coincidence, 2) "triggering," in which an illness which would have occurred anyway was unmasked by the vaccine, or 3) a true causal relationship.

Evidence for the hypothesis of coincidence included the lack of any statistically significant association with MS to date, and the fact that age and sex distributions of reported adverse events resemble age and sex distributions seen before the vaccine. Evidence in support of an increased risk as precipitating factor was the fact that some studies showed slightly increased risk of MS, though not to a statistically significant degree. Evidence against was that another study showed no increased risk. The group concluded that the evidence for an association between the hepatitis B vaccine and MS was weak, and did not meet the criterion for causality.

Response to this data has shown a rare divergence in public health policies. The French National Network of Public Health, while still recommending the vaccine as useful to pre-adolescents, concluded that, because of differences in individual risk for hepatitis B and for side effects of the vaccine and "the need for a medical consultation including the personal and family history," the vaccination program for pre-teens in the schools would be suspended. This suspension was announced on October 1, 1998. Public health departments in several other countries, along with the World Health Organization, criticized the French government for making a decision based more on politics than on the actual risks, and reaffirmed existing vaccination policies. The US Congress held hearings on the subject, while the CDC affirmed that "The scientific evidence to date does not support hepatitis B vaccination causing MS or other demyelinating diseases." (http://www.cdc.gov/nip/vacsafe/fs/qhepb.htm#7) Several organizations concerned with hepatitis B and multiple sclerosis, in the US and Canada, came out with statements supporting continued hepatitis B vaccination.

As I write this section of the FAQ, the CDC reports that at least six research projects are underway, in the US, France, and the UK, to examine what relationship, if any, exists between the hepatitis B vaccine and multiple sclerosis. In the meantime, most countries are continuing to recommend universal hepatitis B vaccination for infants and for pre-teens who have not already been vaccinated.

Q3e.9 When is the hepatitis B vaccine contraindicated?

Sensitivity to yeast or any other component of the vaccine. Pregnancy is not a contraindication to hepatitis B vaccination. A previous anaphylactic response to the vaccine is a contraindication to further doses.

Vaccine components capable of causing adverse reactions: aluminum phosphate, thimerosal, and formaldehyde (Travel Medicine Advisor). (Note, though, that as of September 1999, a thimerosal free hepatitis B vaccine is available.)

Q3e.10 Why did the ACIP and AAP change their recommendation about the hepatitis B vaccine?

Up until 1992, the recommendation was that hepatitis B vaccine be given only to people in high risk groups for hepatitis B: people whose professions exposed them to blood, people at extra risk due to their sexual practices or intravenous drug use, and certain populations (such as Southeast Asian immigrants) with a high incidence of the disease. The chief reason was cost; it was felt to be not cost-effective to vaccinate low-risk groups.

Unfortunately, this policy was not successful in checking the spread of hepatitis B. It proved difficult to identify high-risk people, and high-risk people did not volunteer in large numbers to be vaccinated. For this reason, in 1992, the ACIP recommendation was switched to vaccination of teens and adults in high-risk groups and universal vaccination of infants. The AAP made a similar recommendation but would also like to extend hepatitis B vaccination to all adolescents, if possible.

The American Liver Foundation also supports hepatitis B vaccination of infants, and their pamphlet on the subject suggests a variety of ways in which even young children could come in contact with the virus (through contact with blood, etc.). Though young children are at low risk of catching hepatitis B, their risk of developing the chronic form of the disease if they do catch it is higher than for adults.

The new policy was well-received internationally, and 30 countries now have universal infant HBV vaccination programs. Many physicians remain skeptical, however, and a survey in North Carolina showed one third of pediatricians and <20% of family physicians supporting the new guidelines (Journal Watch, 9-1-93). (Update: Journal Watch for Jan 15, 1995/Feb 7, 1995 reports that this vaccine is gaining physician acceptance, citing Arch Pediatr Adolesc Med Sep 1994, p. 936)

Why the resistance? One reason is a reluctance to give low-risk infants yet another vaccination. Another is doubt about the duration of HBV vaccine. There is evidence that it lasts up to 10 years, but we do not know yet whether it wears off beyond that point. There is concern that infants vaccinated for HBV may lose immunity during adolescence, when the risk of catching the disease is greatest. An alternative would be to vaccinate all children at age 10 and give a booster at age 20. But compliance would likely be lower at age 10 than in infancy. Hepatitis B vaccine is administered in three shots over the course of six months, and it would be difficult to get preteens to all come in for the full series. Also, 8% of hepatitis B infections occur before age 10, and the deadly form is three times greater in children (NY Times, 3/3/93:B8). Boosters could be given later to infants vaccinated for HBV if immunity proves to lapse.

Hepatitis B vaccine is also often recommended for travel purposes.

Q3e.11 Does vaccination for hepatitis B affect one's ability to donate blood?

*************************************************************************
From Gregory Froehlich, MD (from a posting to sci.med):

First, hepatitis B *antigen* is used to make Hep B vaccine.  The
antigen is grown in yeast culture; formerly, it was purified from the
blood of people who were chronic hepatitis carriers. Antibodies are
used in the gamma globulin shots used for hepatitis A or for passive
immunization against hepatitis B if you're exposed.

The local blood bank does not specifically test for exposure to
hepatitis A (the kind you'd get from contaminated water).  If a person
has an active hep A infection, it will be picked up by elevated liver
enzymes; if the person had such an infection in the past, it's over and
done with--hep A doesn't give you a chronic, subclinical infection.
Antibodies to hepatitis A should not preclude blood donation.

They check for chronic hep B carriers by testing for hep B surface
antigen.  They test for recent hep B infection by testing for hep B
core antibody.  This antibody does not carry disease, but rather
indicates that the person was recently infected and might or might not
still be infectious.  They do not test for surface *antibody*, which
would indicate either (a) former hep B infection which was cleared, or
(b) immunization against hep B--in either case, not infectious.  I've
got hep B surface antibody, because I was immunized; I can still donate
blood.

Blood banks also test for hepatitis C antibody; people with this
antibody can still be infectious.
*************************************************************************

Q3e.13 I will be travelling to an area where hepatitis B shots are recommended, but I have less than six months before I leave. Is there an accelerated schedule for hepatitis B vaccination?

_Travel Medicine Advisor_ lists an accelerated schedule, with 3 doses at 0, 30, and 60 days. With this schedule, a fourth dose is recommended at 12 months if there is still a risk for hepatitis B exposure.

Section 1 of the misc.kids Childhood Vaccinations FAQ
Section 3 of the misc.kids Childhood Vaccinations FAQ
Section 4 of the misc.kids Childhood Vaccinations FAQ
Back to the Childhood Vaccinations page of the Children's Health page