Vaccines Get New Scrutiny
Vaccinations are supersafe, but maybe not all at once, or for certain children
Call for study. Far more quietly, the government is acknowledging that, at the moment, science doesn't know much about how many shots a kid can safely get at once and which children will be harmed. Last March, the family of 9-year-old Hannah Poling won a claim in the federal Vaccine Court (created to protect manufacturers from ruinous lawsuits) that the autism she developed as a toddler was most likely triggered by receiving five shots against nine diseases in one day; all told, the government has paid out more than $900 million for vaccine injuries over the past two decades. Since the Poling verdict, the government has called for new safety studies—to evaluate, say, whether gene variations may make some kids more susceptible to vaccine injury. "If we can show that individuals of a certain genetic profile have a greater propensity for developing adverse events, we may want to screen everyone prior to vaccination," says Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, a key partner in the new initiative.
The concern that vaccines might trigger autism was first sparked a decade ago by a British study—since refuted—showing that the measles part of the measles-mumps-rubella shot caused intestinal inflammation and allowed toxins to enter the bloodstream and attack the central nervous system. Other experts speculated that thimerosal, a preservative containing mercury, was the culprit, and it was removed from children's vaccines in 2001 (though most flu vaccines still contain it). The CDC is currently conducting a study of 1,200 children to see whether a thimerosal-autism link really does exist, while some scientists wonder whether a small percentage of cases are, like Hannah Poling's, triggered by multiple vaccinations. Poling was found to have mitochondrial disease, a nerve disorder causing autismlike symptoms that appeared to be brought on by her immunizations. "Mitochondrial disease often occurs in the later stages of a viral illness, and it's proper reasoning to think that vaccines could do what viruses do," in terms of immune reactions, says neurologist Bruce Cohen, a mitochondrial disease expert at the Cleveland Clinic.
A search for markers. The answer could lie in gene studies. "We'd like to know if there are particular markers that signal undetectable diseases like a subclinical mitochrondrial disorder," says Fauci. A 2007 study already found that certain mutations affect a person's susceptibility to fevers after smallpox vaccination; the researchers say they may also predict other responses, like febrile seizures linked to the MMR vaccine.
It's important to keep the risks in perspective: More than 95 percent of kids sail through their shots with, at most, a little fussiness, according to Renee Jenkins, president of the American Academy of Pediatrics. A small percentage experience an overactive immune response like redness, swelling, or pain at the injection site, high fever, or extreme irritability, but severe complications like anaphylactic shock are extremely rare (see graphic). Still, how to account for the fact that once familiar diseases like measles and mumps have become nearly as rare as the adverse reactions?
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