Influenza vaccines containing thimerosal have come under scrutiny following a recent meeting of the Advisory Committee on Immunization Practices (ACIP) in June 2025. The committee, with its newly appointed members, voted against the use of thimerosal-containing influenza vaccines in three separate votes. This decision has raised concerns due to the process and information used during the meeting.
Thimerosal is a preservative that contains ethylmercury and was removed from most childhood vaccines by 2001. However, it remains in some multi-dose vials of influenza vaccines. Despite evidence indicating that thimerosal does not harm health, the ACIP’s decision was influenced by a presentation from a “private citizen” associated with an anti-vaccine group. The presentation did not undergo typical review processes by CDC scientists or involve input from larger stakeholder groups.
The removal of a CDC-prepared document supporting thimerosal’s safety from their website further fueled concerns about transparency and reliability in decision-making processes. Additionally, there are worries about potential disruptions to vaccine supply, as many healthcare providers have already ordered their stock for the upcoming flu season.
In another development, measles cases in the U.S. have surged to their highest levels in 25 years. Measles had been declared eliminated in 2000 but is now spreading continuously due to decreased immunization rates in certain areas. If this trend continues through January 2026, the U.S. risks losing its status as a country that has eliminated measles.
This resurgence has led to more infections than any outbreak over the past three decades and resulted in three deaths this year alone, equaling the total number of measles-related deaths over the last 25 years combined.
