A startling new vision of vaccination in America is becoming clearer — one likely to involve fresh scrutiny of established science and practices, and limits on vaccines that have been studied for decades.

Thimerosal is a preservative that’s been used primarily in multi-dose vaccine vials to prevent contamination with germs. It contains a form of mercury different from the toxic form found in fish, and studies have shown consistently that it does not pose health risks,

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.