On June 26, 2025, the Advisory Committee on Immunization Practices (ACIP) of the CDC voted 5-1 in favor of recommending that everyone in the United States aged 6 months and older receive a yearly flu shot. 

They also advised opting for thimerosal-free vaccines whenever feasible. 

Thimerosal, a mercury-based preservative used in multi-dose vaccine vials, has been under scrutiny since 1999 when federal agencies recommended its removal from most childhood vaccines as a precaution, despite no evidence of harm at low doses. 

Currently, the majority of flu vaccines in the U.S. are thimerosal-free, with single-dose pre-filled syringes widely accessible. 

The ACIP's recommendation is largely symbolic, aimed at addressing public concerns and reducing vaccine hesitancy. 

The CDC maintains that thimerosal is safe, highlighting that scientific studies have found no link between thimerosal in vaccines and health risks.