Conversations about the CDC’s Advisory Committee on Immunization Practices June 25 and 26 meeting are trending online. Although vaccine opponents applauded the replacement of ACIP’s panel of experts with several well-known vaccine skeptics, critics noted that most replacement ACIP members lack relevant expertise and have histories of anti-vaccine work. Days before the meeting, two senators, including one who voted to confirm Kennedy, called for the meeting to be delayed until members “with more direct relevant expertise” are appointed.
The meeting included a presentation about thimerosal, led by the former head of an anti-vaccine organization who has been appointed to an unknown position at the HHS. Thimerosal has long been a focus of the anti-vaccine movement, which falsely claims the vaccine ingredient is harmful and linked to developmental disorders. Research has consistently shown no safety concerns associated with thimerosal, which is present in a small percentage of flu vaccines in the U.S. The thimerosal presentation drew harsh criticism, including from an ACIP member who noted that “the risk from influenza is so much greater than the non-existent, as far as we know, risk from thimerosal.”
Several news outlets also reported that the presentation cited a study that does not exist, in line with the current HHS’s recent trend of referencing nonexistent research. HHS Secretary Robert F. Kennedy Jr. published a long social media post falsely claiming that thimerosal is unsafe, citing outdated and irrelevant studies about methylmercury (contained in thimerosal), which is not present in any vaccine. The post received over 1,300 replies, with many of the top responses noting accurately that thimerosal contains ethylmercury, a form of mercury that humans can safely process and which decades of research have shown is completely harmless in the doses present in vaccines.
Many social media users feared that Kennedy’s health officials and advisors may be laying the groundwork to restrict access to or ban certain vaccines. These fears were validated by ACIP’s vote against recommending flu vaccines containing thimerosal. Although few vaccines in the U.S. contain the ingredient, many online critics emphasized that the vote was based on disproven claims about the alleged risk posed by the substance, which has been safely used in vaccines worldwide for decades.
Recommendation
The upheaval at the CDC, delayed ACIP votes, the appointment of anti-vaccine figures to ACIP, and the inclusion of anti-vaccine talking points at the June meeting may cause uncertainty about the agency’s stance on certain vaccines and erode public trust. Health communicators may emphasize that all vaccine ingredients are rigorously tested for safety and added to make vaccines safer and more effective. Highlighting how vaccine opponents misuse fake and non-credible research to promote anti-vaccine messages is also recommended.
Debunking messaging may explain that thimerosal is a vaccine preservative that prevents contamination. It contains ethylmercury, a form of mercury that is safe for humans in small doses. Few vaccines in the U.S. contain thimerosal, and those that do have roughly the same amount of mercury as a can of tuna. Thimerosal was removed from all routine childhood vaccines in the U.S. in 2001 as a precautionary measure. Decades of research have never found evidence that thimerosal in vaccines is harmful.
Many countries worldwide use thimerosal-containing vaccines with no safety issues. In the U.S., the only vaccines that contain thimerosal are a small percentage of flu vaccines stored in vials with multiple doses and a tetanus and diphtheria vaccine for individuals aged 7 and older.
Fact-checking sources: Your Local Epidemiologist, PBS News, The Conversation
