A new slate of vaccine advisers to the US Centers for Disease Control and Prevention voted Thursday to recommend that Americans receive influenza vaccines that are free of thimerosal even though there is no evidence of harm from the preservative.

A CDC advisory panel voted 5–1 to recommend only flu vaccines without the preservative thimerosal, a mercury-containing compound used as a preservative in vaccines and other drugs. Doctors and physician advocacy groups warn that the decision could fuel vaccine hesitancy.

U.S. Health Secretary Robert F. Kennedy Jr.'s newly revamped vaccine advisory panel voted on Thursday to recommend Americans receive seasonal influenza shots that are free from the mercury-based preservative thimerosal despite decades of studies showing no related safety issues.