Posts mislead on Gardasil shot safety

"AB659 would require children 8-12th grade to receive the HPV (vaccine) in order to attend school. Gardasil is the ONLY available HPV (vaccine) in the US," says a March 17, 2023 Instagram post from California Freedom Keepers, a group that advocates against health mandates.

Text in the post's three-slide carousel claims the Gardasil 9 vaccine contains "toxic aluminum" and polysorbate 80, which "has been shown to cause cancer in animals." Other Instagram accounts reshared the claims, racking up hundreds of additional interactions.

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Screenshot of an Instagram carousel taken March 29, 2023

The post followed the California legislature's introduction of the Cancer Prevention Act (AB-659) in February 2023. If the bill is passed it would require all students at public and private schools to receive the HPV vaccine before eighth grade.

Merck's Gardasil 9 vaccine helps prevent diseases caused by nine types of HPV, the most common sexually transmitted infection. The US Food and Drug Administration (FDA), Health Canada and the European Medicines Agency (EMA) have all approved the shot.

The vaccine does contain aluminum and polysorbate 80, but not at levels that experts say would be harmful. And the jab has been continually monitored for safety.

"The overwhelming body of scientific evidence -- which includes more than 20 years of research and development -- continues to support the safety and efficacy profile of our HPV vaccines," Merck said in a statement emailed to AFP on March 30.

The US Centers for Disease Control and Prevention (CDC) says on its website that a 2019 study published in the journal Pediatrics did not identify any unexpected safety concerns with Gardasil 9. The most common side effect is "pain, swelling, and redness in the arm where the shot was given," according to the CDC.

Allergic reactions, some serious, are possible following any vaccine. Gardasil 9 is not recommended for those allergic to yeast or people who have previously had allergic reactions to vaccines.

AFP took a closer look at three claims in California Freedom Keepers' Instagram post.

Aluminum

Claim: "Gardasil 9 contains 500 micrograms of toxic aluminum in the form of amorphous aluminum hydroxyphosphate sulfate."

Amorphous aluminum hydroxyphosphate sulfate (AAHS) is in Merck's HPV vaccine, according to the FDA. But calling the amount in a single dose "toxic" is false.

AAHS is included as an adjuvant, an ingredient that can trigger a stronger immune response. Vaccines in the US have contained aluminum adjuvants for six decades -- and federal regulations indicate they are safe if the dose is 1.25 milligrams or less.

The package insert for the Gardasil 9 vaccine says each dose "contains approximately 500 mcg of aluminum (provided as AAHS)" -- well within the limit.

Other ingredients in Merck's shot include "proteins of HPV Types 6, 11, 16, and 18, yeast protein, sodium chloride, L-histidine, polysorbate 80, sodium borate, and water for injection," according to the FDA.

Polysorbate 80

Claim: "Polysorbate 80 has been shown to cause cancer in animals and linked to numerous autoimmune issues and infertility."

This is misleading.

Polysorbate 80 (P80) is an emulsifier used in foods including ice cream to help hold ingredients together. Its inclusion in vaccines is a regular target of misinformation.

Andrew Gewirtz, a professor at Georgia State University who researches the effects of emulsifiers such as P80, said he has found links to cancer. But he dismissed claims that vaccine recipients would be at risk.

"I don't think the chronic daily administration we used in mice and humans would be informative (regarding) occasional exposure," he told AFP in a March 23 email.

Gewirtz added that his team found "impacts of emulsifiers was reversible within a month or so after consumption ceased, suggesting any impacts of the P80 from the injection would likely be temporary."

Merck told AFP there has been "no causal association made between HPV vaccination and either autoimmune issues or infertility."

Other studies have found P80 in vaccines is safe.

One examination of pneumococcal vaccines with and without P80 detected no safety concerns. Another study of adjuvants found "no compelling evidence" linking them to autoimmunity.

Research on the effects of Tween 80, another name for P80, on fertility is often cited in claims that vaccines with the compound are harmful. But the amount given to rats in the trial was significantly larger than what humans receive from a shot.

Both the Michigan Mott Children's Hospital and the Children's Hospital of Philadelphia have refuted claims that the use of P80 in vaccines could cause infertility.

Blood-brain barrier

Claim: "Polysorbate 80 makes the blood brain barrier more permeable and allows chemicals that otherwise would not be allowed into the brain to cross through the barrier."

This is also misleading.

Zhenpeng Qin, an associate professor of mechanical engineering at the University of Texas at Dallas who helped develop a technique to open the blood-brain barrier temporarily to deliver medication to the brain, said getting through the network of blood vessels and tissue "is not easy."

There is research supporting the use of P80 for delivering drugs to the brain, he said March 23, but only in "very specific formulations" or when administered intravenously in large quantities.

For vaccines injected into muscles, he said it is "very unlikely that the tiny amount of polysorbate 80 is going to have any observed impact on the blood-brain barrier."

Cosby Stone Jr, an assistant professor of medicine at Vanderbilt University, has also dismissed that possibility.

"If you work really hard at it you can attach other things to polysorbate 80 that do make it cross the blood-brain barrier," he told AFP in 2021. "But by itself, just as a stabilizer in a vaccine, that's not something that I'm concerned about at all."

More of AFP's reporting on vaccine misinformation is available here.