WSJ: Controversial Study Reignites Debate Over Autism and Childhood Vaccines

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Controversial Study Reignites Debate Over Autism and Childhood Vaccines

Wall Street Journal

September 7, 2004

Health Journal

By Tara -Pope

healthjournal@...

Just a few months after the nations’ top medical adviser rejected a link

between vaccines and autism, a mouse study has reignited the debate and

raised new fears among parents considering vaccinations and flu shots for

their kids.

For years, a cadre of parents and physicians have contended that thimerosal,

an ethyl-mercury compound that has been one of the most widely used vaccine

preservatives, is partly responsible for an apparent rise in autism in

recent decades. But broad population studies haven't supported the claim.

In May, a major report from the Institute of Medicine's Immunization Safety

Review Committee sought to put the debate to rest, rejecting a link between

autism and vaccines. But tomorrow, a congressional committee will review a

June study from Columbia University, which found that a mercury preservative

used in vaccines can indeed cause autism-like symptoms in a specific strain

of mice.

The research raises important questions about whether some people might be

genetically vulnerable to the effects of thimerosal. The study also raises

questions about a new push by the Centers for Disease Control and Prevention

to add flu shots to the immunization schedule for school-age kids.

Thimerosal has been mostly phased out of childhood vaccinations, which

include shots for whooping cough and other illnesses. But the vast majority

of flu shots given to both adults and children still contain the

preservative. In addition, it's widely believed that many unexpired vials of

thimerosal-containing childhood vaccines remain on the shelves of

pediatricians’ offices.

None of this is to say that parents should stop having their children

vaccinated. Instead, critics of thimerosal say parents should insist on

thimerosal-free vaccines and ask to check the label themselves before a

child receives a shot. Many researchers believe increased use of vaccines

with thimerosal may help explain the alarming rise in autism in the U.S.,

which was just 1 in 2,500 children 20 years ago.

Now CDC studies show the rate for autistic disorders in some areas to be as

high as 1 in 150. But the IOM report said an exhaustive review of the

evidence doesn’t support the claim that vaccines are to blame. The finding

has sparked the ire of many autism researchers as well as parents who are

convinced that vaccinations triggered autism in their kids.

Among them is Congressman Dan Burton, an Indiana Republican, whose grandson

developed autism five years ago after receiving shots containing thimerosal.

Rep. Burton is chairman of the subcommittee that this week will hold

hearings on the mouse study and other research. " We just need to get the

mercury out of vaccinations, " says Rep. Burton.

What is so frustrating to critics of the IOM report is that thimerosal is an

entirely unnecessary ingredient. The mercury preservative typically is found

in multi-dose vials to prevent contamination. But vaccines can be packaged

in single doses and other preservatives can be used to protect multi-dose

packs. Thimerosal remains in use in flu shots and adult vaccines mainly

because of the cost of changing ingredients or switching to single-dose

shots.

" We have other ways to make vaccines safe, " says Ellen Silbergeld, professor

of environmental health sciences at s Hopkins Bloomberg School of Public

Health. The new mouse study bolsters the theory that genes involved in the

immune system might make some people vulnerable to mercury -- explaining why

the vast majority of kids do fine after vaccines while a small number

develop problems.

In the Columbia study, researchers administered thimerosal to four strains

of young mice, injecting them with amounts comparable to those given to

kids. Three of the mice strains were unaffected by thimerosal, but the

fourth developed problems consistent with autism such as delayed growth,

social withdrawal and brain abnormalities. The vulnerable mice were known to

have a specific genetic susceptibility to mercury.

While a mouse study is far from conclusive, it's important to know that mice

have long been a useful proxy for understanding human health. The

researchers are close to developing a blood test to look for similar

patterns in autistic children to see if the research translates to humans.

Until more is known, says Mady Hornig, associate professor of epidemiology

at Columbia’s Mailman School of Public Health, " I think we should err on the

side of caution and more thimerosal-free vaccines should be available. "

Other experts say the mouse study offers little insight into the issue, but

is needlessly upsetting parents and could undermine the nation’s childhood

vaccination program. Unproven worries about autism and vaccines are

" hypothetical " compared to " a very real risk of disease, " notes Marie

McCormick, professor of maternal and child health at Harvard School of

Public Health and chairwoman of the IOM committee.

Parents concerned that a pediatrician may have an old vial of

thimerosal-containing vaccine can politely ask to see the label. Most

doctors understand that parents can be nervous about vaccinations, says Ian

Lipkin, director of the Center for Immunopathogenesis and Infectious

Diseases at Columbia University and co-author of the mouse study.

In addition, you can check Food and Drug Administration charts listing

vaccines and their thimerosal status at

<http://www.fda.gov/cher/vaccine/thimerosal.htm>. Many doctors and clinics

may not have a supply of thimerosal-free flu shots. Calling in advance may

give a doctor enough time to obtain a single-dose syringe. Another option to

ask for is Flu-Mist, a nasal mist vaccine that doesn't contain thimerosal.