This Vaccine Preservative Is Again Under Scrutiny. What Does the Science Show?
For decades, anti-vaccine groups have targeted thimerosal, a vaccine preservative that they claim, without credible evidence, is linked to autism and other neurodevelopmental disorders.
These claims about the mercury-based preservative have long existed at the fringes — until now.
Under the leadership of the health secretary, Robert F. Kennedy — who wrote a book supporting 'the immediate removal of mercury' from vaccines — these claims are now to be seriously considered by newly appointed members of the Advisory Committee on Immunization Practices, an influential group that makes vaccine recommendations to the Centers for Disease Control and Prevention.
On Thursday, the panel is expected to discuss and vote on the use of thimerosal in flu vaccines, the only routine shots that still include the additive. Instead of a C.D.C. scientist presenting on the subject, as is custom, Lyn Redwood, the former leader of a prominent anti-vaccine group, will speak to the committee.
Slides from that presentation, which were posted online ahead of the meeting, argue thimerosal is 'neurotoxic' and harmful for pregnant women and children — claims that are contradicted by dozens of rigorous studies and have largely been rejected by vaccine scientists.
Why is thimerosal used in vaccines?
Scientists started using thimerosal as a preservative in vaccines in the 1930s. The preservative can prevent vials that contain multiple shots from becoming contaminated when new needles draw out a dose.
Today, it is rarely used in routine vaccines. During the last influenza season, roughly 96 percent of all flu shots in the United States were thimerosal-free, according to data from the C.D.C.
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