Thimerosal Will Be Removed From Flu Shots. Is It Actually Toxic?
The Department of Health and Human Services (HHS) has decided to follow a recommendation to take thimerosal out of all flu vaccines in the United States.
An advisory group at the Centers for Disease Control and Prevention (CDC) suggested this change, even though there’s no clear proof that thimerosal is harmful and most flu shots in the U.S. already don’t have it.
What Is Thimerosal and Why Is It Used in Vaccines?
Thimerosal is a preservative that contains mercury.
It is used to stop bacteria from growing in multi-dose vials of vaccines and other medicines.
A few years ago, some reports worried that thimerosal might be linked to developmental and cognitive problems in children, including autism.
But no real studies have confirmed that link.
In 1999, thimerosal was removed from most vaccines “out of an abundance of caution,” according to Robert Hopkins Jr, MD, medical director of the National Foundation for Infectious Diseases.
Almost all vaccines are now available without thimerosal.
About 94% of the U.S. flu vaccine supply doesn’t contain it. Those that do are usually in multi-dose vials used in some rural clinics.
“The data has shown that thimerosal isn’t harmful in the small amounts previously used, and today, most people can easily avoid vaccines that contain it,” Hopkins said.
Is Thimerosal Safe?
There are two types of mercury.
Methylmercury, which is found in some fish, can be harmful in large amounts. Ethylmercury, the type in thimerosal, is removed from the body faster, making it less likely to be harmful.
The CDC says thimerosal has a good safety record in medical products, and many studies have found no harm from the small doses used in vaccines.
“This fact was clearly decided years ago, and the FDA, the CDC, and many academic institutions have thoroughly reviewed the safety of thimerosal-containing vaccines in children.
Raising this topic now only aims to create distrust in vaccines and the process of determining vaccine safety,” James Campbell, MD, MS, FAAP, a member of the American Academy of Pediatrics Committee on Infectious Diseases, said in a statement.
Hopkins also pointed out that chemical ingredients in vaccines have often been the target of anti-vaccine messages.
He tells patients that while many chemicals can be harmful, the key is how much you get. “We all need iron, but too much can be damaging,” he added.
Only one new member of the Advisory Committee on Immunization Practices (ACIP) voted against the recent recommendation to remove thimerosal.
H. Cody Meissner, MD, a professor of pediatrics at the Dartmouth Geisel School of Medicine, said during the panel, “The ACIP makes recommendations based on scientific evidence as much as possible... and there is no scientific evidence that thimerosal has caused a problem.”
Thimerosal Controversy Sparks Concern Over Vaccine Access and Trust
Thimerosal wasn’t on the original agenda for the ACIP meeting.
But the topic was added after HHS Secretary Robert F. Kennedy Jr. removed all 17 existing ACIP members—usually vetted by the CDC—and replaced them with his own appointees.
According to news reports, several of these new members have publicly doubted the safety of vaccines.
The CDC has not yet agreed with the committee’s recommendation to stop using thimerosal in flu shots.
Infectious disease experts worry that the ACIP vote might increase vaccine hesitancy and reduce flu shot access, especially in underserved areas.
Angela Branche, MD, an infectious disease specialist at the University of Rochester, said at a briefing by the Infectious Diseases Society of America that many rural clinics don’t have enough space to store single-dose vials.
The change would mean “a monetary cost for these clinics and a cost in who gets vaccinated,” Branche said.