A Centers for Disease Control and Prevention advisory panel vote to recommend against use of seasonal influenza vaccines containing small amounts of thimerosal followed a presentation that misled on the risks of the rarely used preservative.
There isn’t evidence that thimerosal in vaccines is harmful, and studies assessing a variety of health problems, including neurological conditions, have supported its safety.
Despite this, a June 26 presentation by longtime anti-vaccine advocate Lyn Redwood, given before the Advisory Committee on Immunization Practices, made unfounded or misleading claims, including that thimerosal is ineffective and a neurotoxin. (ACIP, which has been guiding the CDC’s vaccine recommendations since 1964, was recently completely reconstituted by Health and Human Services Secretary Robert F. Kennedy Jr., in an unprecedented move.)
Thimerosal, which is mercury-based, has long been a focus of anti-vaccine groups, including Children’s Health Defense, the nonprofit founded and formerly chaired by Kennedy. He has credited Redwood, a retired nurse practitioner who was also involved in the founding and past leadership of the nonprofit, as one of the people who introduced him 20 years ago to the thoroughly debunked claim that thimerosal in vaccines causes autism.
Thimerosal has been used in vaccines since the 1930s but in the U.S. today is only present in flu shots taken from multidose vials, as the preservative is needed to prevent the growth of germs that could be introduced each time a needle enters the vial. In 1999, the Food and Drug Administration asked that vaccine manufacturers stop offering thimerosal-containing versions of vaccines routinely given in infancy as a precautionary measure, even though there wasn’t evidence of harm. Since 2001, no vaccines for children have included thimerosal, except for some flu vaccines.