Two recent studies reported rising cancer rates among younger adults in the U.S. and worldwide. This prompted some online anti-vaccine accounts to link the studies’ findings to COVID-19 vaccines. 

But, as with other myths, the data tells a very different story. 

What you need to know 

• Baseless claims that COVID-19 vaccines cause cancer have persisted online for several years and gained traction in late 2023.
• Two recent reports finding rising cancer rates among younger adults are based on pre-pandemic cancer incidence data. Cancer rates in the U.S. have been on the rise since the 1990s.
• There is no evidence of a link between COVID-19 vaccination and increased cancer risk.

False claims about COVID-19 vaccines began circulating months before the vaccines were available. Chief among these claims was misinformed speculation that vaccine mRNA could alter or integrate into vaccine recipients’ DNA. 

It does not. But that didn’t prevent some on social media from spinning that claim into a persistent myth alleging that mRNA vaccines can cause or accelerate cancer growth. Anti-vaccine groups even coined the term “turbo cancer” to describe a fake phenomenon of abnormally aggressive cancers allegedly linked to COVID-19 vaccines. 

They used the American Cancer Society’s 2024 cancer projection—based on incidence data through 2020—and a study of global cancer trends between 1999 and 2019 to bolster the false claims. This exposed the dishonesty at the heart of the anti-vaccine messaging, as data that predated the pandemic by decades was carelessly linked to COVID-19 vaccines in viral social media posts.

Some on social media cherry-pick data and use unfounded evidence because the claims that COVID-19 vaccines cause cancer are not true. According to the National Cancer Institute and American Cancer Society, there is no evidence of any link between COVID-19 vaccines and an increase in cancer diagnosis, progression, or remission. 

Why does the vaccine cancer myth endure?

At the root of false cancer claims about COVID-19 vaccines is a long history of anti-vaccine figures falsely linking vaccines to cancer. Polio and HPV vaccines have both been the target of disproven cancer myths. 

Not only do HPV vaccines not cause cancer, they are one of only two vaccines that prevent cancer.

In the case of polio vaccines, some early batches were contaminated with simian virus 40 (SV40), a virus that is known to cause cancer in some mammals but not humans. The contaminated batches were discovered, and no other vaccine has had SV40 contamination in over 60 years. 

Follow-up studies found no increase in cancer rates in people who received the SV40-contaminated polio vaccine. Yet, vaccine opponents have for decades claimed that polio vaccines cause cancer.

Recycling of the SV40 myth

The SV40 myth resurfaced in 2023 when vaccine opponents claimed that COVID-19 vaccines contain the virus. In reality, a small, nonfunctional piece of the SV40 virus is used in the production of some COVID-19 vaccines. This DNA fragment, called the promoter, is commonly used in biomedical research and vaccine development and doesn’t remain in the finished product. 

Crucially, the SV40 promoter used to produce COVID-19 vaccines doesn’t contain the part of the virus that enters the cell nucleus and is associated with cancer-causing properties in some animals. The promoter also lacks the ability to survive on its own inside the cell or interact with DNA. In other words, it poses no risk to humans.

Over 5.6 billion people worldwide have received COVID-19 vaccines since December 2020. At that scale, even the tiniest increase in cancer rates in vaccinated populations would equal hundreds of thousands of excess cancer diagnoses and deaths. The evidence for alleged vaccine-linked cancer would be observed in real incidence, treatment, and mortality data, not social media anecdotes or unverifiable reports. 

This article first appeared on Public Good News and is republished here under a Creative Commons license.