Vaccine Verity: New Studies Weigh Benefits And Risks

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Pretty disgusting article - I just posted the response by at whaleto..

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PUBLIC HEALTH

Vaccine Verity: New Studies Weigh Benefits And Risks

[by Damaris Christensen in Science News Online, Vol. 160, No. 7.]

http://www.sciencenews.org/20010818/bob17.asp

Smallpox. Measles. Mumps. Polio. These words once conjured up images

of people with severe rashes, swollen jaws, or paralysis. Yet vaccines have

eliminated smallpox and made the rest of these once-common,

often-debilitating diseases rare.

The percentage of people vaccinated against these diseases is at an

all-time high, while death rates from them are at all-time lows. But the

very success of these vaccines, plus those for meningitis and a variety of

other diseases, carries with it the germ of a public health tumult.

As more people are vaccinated, the trauma of the original diseases

becomes rare=97but harmful side effects of vaccines may garner more=

attention.

Furthermore, inaccurate information now spreading through the Internet

exacerbates worries about vaccine safety, public health specialists say.

Although commitment to vaccine use in the United State remains high,

health professionals worry that parents' fears of vaccine side effects may

come to outweigh their appreciation of the benefits of vaccination for their

children.

Reports of side effects that she gathered from the Internet

contributed to the decision by Suzanne Walther of Murfreesboro, Tenn., to

postpone giving any vaccines to her third child, .

Unfortunately, her daughter developed a vaccine-preventable case of

meningitis just before her first birthday. recovered fully,

but children with such an infection can become mentally retarded or die.

" These diseases weren't tangible to me [before 's

illness], but I saw all these horror stories about adverse reactions parents

attributed to vaccines, " Walther says. " I only wanted to vaccinate if it was

the best thing for my child. "

Several new, large studies counter some recent vaccine scares. Other

work is investigating how parents' individual decisions against vaccinating

their children might increase other children's risk of disease.

" There is no thing you can do, there is no food you can eat, there is

no vaccine you can get that is 100 percent effective and 100 percent safe, "

says A. Poland of the Mayo Clinic and Foundation in Rochester, Minn.

By and large, he says, vaccines are some of the safest and most effective

medical interventions in existence. " It is legitimate to raise safety

concerns, " he says, " but we can't throw these unparalleled advances away. "

Rare Side Effects

Concerns about vaccine safety aren't new. A hundred years ago,

residents in Boston protested mandatory smallpox vaccinations. Research has

linked a few vaccines to rare side effects far more serious than the typical

fever and swelling at the injection site.

About 3 in 100,000 kids given the combined vaccine for diphtheria,

tetanus, and pertussis develop breathing difficulties or seizures. Just 1 in

100,000 kids vaccinated against measles, mumps, and rubella develop high

fevers or some loss of consciousness. By way of comparison, 11 of 100,000

pregnant women die in childbirth.

Some vaccines can on rare occasions cause problems by actually

infecting a person with a disease that the inoculation is intended to

prevent. For example, in two cases over the past 50 years of worldwide polio

vaccination, outbreaks of polio have been traced to viruses that mutated

after being introduced as part of a live vaccine. In other cases, people

given the varicella, or chicken pox, vaccine as children later experienced

herpes zoster, or shingles, a painful reactivation of the virus. This

complication, however, occurs more often in people who experienced chicken

pox than in those who were immunized.

In 1999, Wyeth Laboratories of Marietta, Pa., withdrew a vaccine

against rotavirus after just a year on the market. Rotavirus infection can

cause diarrhea and sometimes death, but the vaccine slightly increased the

risk of potentially fatal intestinal blockages.

Some parents' worries don't focus on a specific vaccine effect.

Current federal recommendations include 20 injections in a child's first 18

months and several other immunizations over the next 10 to 15 years to

protect against 11 diseases. Despite a lack of scientific evidence

supporting their concerns, " One in four parents of children under 6 believes

their children's immune systems could be weakened by too many vaccines, "

says Bruce Gellin of Vanderbilt University in Nashville, " and almost as many

believe that children get more immunizations than are good for them. "

Gellin, who is also executive director of the National Network for

Immunization Information in andria, Va., recently surveyed 1,600 parents

with young children.

Despite their concerns, 87 percent of the parents agreed that

vaccinations are important to keeping their children healthy, Gellin

reported in the Nov. 5, 2000 Pediatrics.

Concerns Over Safety

Gregg Burgess, a parent of two in Sterling, Va., hasn't immunized his

two boys. He feels that the number of vaccines given kids these days can

cause their immune systems to get " screwed up, " perhaps resulting in autism

and autoimmune disorders like diabetes. Burgess is a board member of the

National Vaccine Information Center, an antivaccine [sic] group that claims

there isn't enough evidence to demonstrate the safety of vaccines.

If parents' fears over vaccine safety rise, public health officials

worry that immunization rates will drop. Such a decline would naturally lead

to more cases of disease among the unvaccinated children. Because most

vaccines don't provide complete protection against disease in every child,

however, even vaccinated children would become more vulnerable if

vaccination rates drop, scientists predict.

In Colorado, an unusually large contingent of parents holds religious

or philosophical objections to vaccination. Among that state's school-age

kids, 1.4 percent=97twice the national average=97remain unvaccinated. A=

study in

the Dec. 27, 2000 Journal of the American Medical Association reported that

unvaccinated children were more than 20 times as likely as vaccinated

children to develop measles and almost 6 times as likely to develop

pertussis, also known as whooping cough.

In addition, vaccinated children living in areas with high percentages

of unvaccinated children were significantly more likely to get one of these

infectious diseases than were children in more highly vaccinated areas, says

T. Chen of the Centers for Disease Control and Prevention (CDC) in

Atlanta, an author of the study. For each 1 percent of kids that go

unvaccinated in a county, the researchers calculated that the risk of

measles among vaccinated children rose by 60 percent and the risk of

pertussis rose by 90 percent.

Other researchers have looked at the effects of widespread

vaccine-safety scares in different countries. Eugene J. Gangarosa of Emory

University in Atlanta and his colleagues showed that vaccination rates for

pertussis in the 1970s and 1980s dropped in European countries that had

strong antivaccine campaigns in reaction to concerns about seizures and

brain damage. Soon thereafter, he found, the rates of pertussis in these

countries rose to levels 10 to 100 times as high as those in countries where

antivaccine movements hadn't affected immunization programs.

" There's no question these movements undermine, collectively and

individually, the benefits of vaccination, " Gangarosa says.

Changed Products

Some vaccination side effects have been well documented, and vaccine

makers have changed their products to reduce these effects. In other cases,

however, scientists have been unable to confirm anecdotal links between

vaccines and diseases.

Federal guidelines now recommend a pertussis vaccine that uses only

part of, instead of entire, killed pertussis bacterium and is safer than the

earlier version. Walther says, however, that this change to the so-called

acellular vaccine is not immediately apparent to parents looking for safety

information on the Internet.

Another recent switch in the United States, effective last year,

provides injected polio vaccine instead of the oral version. Despite the

advantages of avoiding shots, the small chance of developing polio=97about 1

case per 750,000 oral vaccinations=97was deemed greater than the chance of

catching polio from another person in this country.

Oral polio vaccines continue to be widely used in developing

countries, where polio is more common and health officials believe the ease

and safety of administering oral vaccines outweigh any risks.

New formulations for many vaccines will soon reach pediatric offices.

Thimerosol, a mercury compound, is an ingredient that prevents bacteria and

fungi from contaminating vaccines. Although no research indicates a problem,

public health officials feared that with the increasing number of vaccines

that each baby receives, low-birth-weight babies might be exposed to too

much mercury. At high doses, the chemical can cause kidney and neurologic

damage.

The new formulations will contain alternative preservatives to

thimerosol or be provided in single-use vials that don't require a

preservative. Researchers and public health officials plan to examine large

databases of health-care and vaccination records to see whether they can

link the mercury of the traditional vaccines to health problems.

A recent set of widely reported vaccine-safety concerns suggested a

link between the measles, mumps, and rubella (MMR) vaccine and autism, a

developmental disorder characterized by a person's difficulty connecting

with others. These concerns were sparked in part by a report published in

1998 in The Lancet, a British medical journal. There, researchers described

12 children who developed autism and similar behavioral problems soon after

vaccination with MMR.

Since the 1998 report, several larger studies including tens of

thousands of children have found no link between MMR vaccination and autism,

and researchers haven't yet demonstrated a plausible biological mechanism

for such a link. Earlier this year, two U.S. committees=97one assembled by=

the

Institute of Medicine (IOM), a federal advisory agency, and another by the

American Academy of Pediatrics=97concluded that the vaccine wasn't behind a

decade-long rise in the number of U.S. children diagnosed with autism.

" There is simply no evidence to support an association between MMR and

autism, " says Marie McCormick of the Harvard School of Public Health in

Boston, who chaired the IOM committee.

Another widely reported concern is that the hepatitis B vaccine leads

to multiple sclerosis, a disease that causes nerve degeneration and muscle

weakness. In the Feb. 1 New England Journal of Medicine, two research teams

concluded that this vaccination doesn't appear to either cause multiple

sclerosis or exacerbate the course of the disease.

One researcher reported that when given to young infants, the vaccine

for the meningitis-causing bacterium Haemophilus influenzae B might trigger

diabetes. So far, however, no study has confirmed that link, says

Mc of the University of Washington School of Medicine in Seattle.

Nor is there research support for the idea that the hepatitis B vaccine

increases the risk of sudden infant death syndrome.

Conflicting Safety Claims

It's easy to understand why parents might associate a vaccine with a

disease whose cause is unknown. Since the administration of vaccines is so

common, the chances are good that disease onset will follow vaccination in

some people, Chen says. The early signs of developmental disorders tend to

show up in the first few years of life, a time when healthy kids are getting

vaccinated often, so conditions such as autism may seem linked to an

immunization even when they are not. Sifting through conflicting safety

claims can be difficult, says Chen.

Many vaccine scares are hard to quell because scientific studies can

never prove that a vaccine doesn't underlie a particular disease, only that

the chances of it being the cause are very low, Poland says. That might

reassure a scientist, but it may not comfort a worried parent.

Moreover, extremely rare side effects of any new vaccine can't be

reliably detected until the vaccine has entered the market and been given to

millions of people. Vaccines then get a lot of publicity. For example, Wyeth

Laboratories tested the rotavirus vaccine on 10,000 infants before it

received governmental approval. In the March 21 Vaccine, A. Poland

of the Mayo Clinic in Rochester, Minn., and his colleagues show that the

bowel problems associated with the rotavirus vaccine couldn't have been

detected unless more than 100,000 infants had been studied.

The risk associated with the rotavirus vaccine's side effects is lower

than the risk of injury associated with most car trips and some antibiotics

given to treat children with infections, Poland says. However, because so

many healthy infants are vaccinated, even infrequent side effects can be

important.

The critical next step for public health professionals is to develop

better ways to identify which kids are most likely to suffer adverse

effects, says Poland. Researchers are currently tracking vaccinations and

health problems in more than 2.5 percent of the U.S. population, and CDC

plans to expand the effort.

" It's a good thing when there's a lot of scrutiny and accountability

about safety, " says Poland.

Such large national databases are going to be increasingly important

tools for monitoring rare side effects, says Chen. " Until recently, the

paradigm for vaccination has been that once the disease has been effectively

eliminated, we'll stop immunizing, thus eliminating vaccine side effects, "

he says. Disease elimination needs to be worldwide because the incubation

period for most infectious diseases is longer than the time required for a

jet flight halfway around the globe. The only vaccine success on this scale

is the fight against smallpox.

Chen has reservations about ending any vaccination programs against

deadly diseases. " In this world of potential bioterrorism, any disease worth

eliminating is also a perfect target for bioterrorists, " he says.

" That means we no longer have the luxury of ignoring even very rare

adverse events, " Chen concludes. " We are never going to be able to stop

immunizing again. "

References:

Ascherio, A., et al.

2001. Hepatitis B vaccination and the risk of multiple sclerosis. New

England

Journal of Medicine 344(Feb. 1):327.Confavreux, C., et al. 2001.

Vaccinations

and the risk of relapse in multiple sclerosis. New England Journal of

Medicine

344(Feb. 1):319.Dittmann, S. 2001. Vaccine safety: Risk communication=97A

global perspective. Vaccine 19:2446.Heijbel, H., and T. Jefferson. 2001.

Vaccine safety=97Improving monitoring. Vaccine 19:2457.son, R.M., et=

al.

2001. Adverse events and vaccination=97the lack of power and predictability=

of

infrequent events in pre-licensure study. Vaccine 19(March 21):2428.Poland,

G.A., and R.M. son. 2001. Understanding those who do not understand: A

brief review of the anti-vaccine movement. Vaccine 19:2440.Further Readings:

2001. CDC's childhood immunization schedule. Morbidity and Morality Weekly

Report. 50(Jan 12):7. Feikin, D.R., ... R.T. Chen, et al. 2000. Individual

and community risks of measles and pertussis associated with personal

exemptions to immunization. Journal of the American Medical Association

284(Dec. 27):3145.Gellin, B.G., et al. 2000. Do parents understand

immunizations? A national telephone survey. Pediatrics

106(November):1097.Peltola, H., et al. 1998. No evidence for measles, mumps,

and rubella vaccine-associated inflammatory bowel disease or autism in a

14-year prosepctive study. Lancet 351(May 2):1327.Poland, G.A. 2000. Vaccine

safety: Injecting a dose of common sense. Mayo Clinic Proceedings

75(February):135.Sources: T. Chen

Centers for Disease Control and Prevention

1600 Clifton Road

MS-C23

Atlanta, GA 30333Eugene J. Gangarosa

5305 Greencastle Way

Stone Mountain, GA 30087-1427Bruce G. Gellin

Department of Preventive Medicine

Vanderbilt University Medical Center

A-1124 MCN

Nashville, TN 37232-2637Marie C. McCormick

Harvard School of Public Health

677 Huntington Avenue

Kresge Maternal and Child Health

Kresge 3

Boston, MA 02115 A. Poland

Department of Medicine

Vaccine Research Group

Mayo Medical School

Rochester, MN 55905

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