The preservative is in a small share of flu shots and has been studied for decades. Experts say it’s safe — despite Kennedy’s long opposition.

"This is a very clear effort to shine a light on this anti-vaccine trope: that thimerosal is somehow dangerous.” ...

Get the latest facts about the symptoms, causes, and treatment options for the flu. Learn expert prevention tips, plus get advice on how to boost immunity and what to know about the influenza vaccine.