Daily Fact-Check: COVID-19 Vaccines Have Not Been Shown to Cause ‘Turbo Cancer’

COVID-19 has killed more than 1.1 million people in the U.S. People with cancer who get COVID-19 have an elevated risk of severe disease and death, especially those who have certain blood cancers. Vaccines help mitigate these risks.

The COVID-19 vaccines can cause largely minor and short-lived side effects, such as fatigue and soreness at the injection site, which have been generally consistent in people with and without cancer. There isn’t evidence to date that COVID-19 vaccines cause cancer or lead to worsening cancer for people who already have it.

However, unsupported claims that the COVID-19 vaccines cause cancer have repeatedly surfaced on social media. “SHOCKING: New Study proves Pfizer mRNA induced turbo cancer,” recent posts have said. They claimed that a single mouse in this study “died suddenly,” a phrase associated with a family of groundless claims that the COVID-19 vaccines are killing large numbers of people.

Sander Eens, a cardiovascular disease researcher at the University of Antwerp who co-authored the study in question, criticized how the social media posts characterized his work. 

“Specifically, our case report has been misinterpreted as evidence that Pfizer/BioNTech’s COVID-19 mRNA vaccine could cause a scientifically unrecognized phenomenon called ‘turbo-cancer,’” he told us in an email.

“Turbo cancer” is a term used by people who claim that the COVID-19 vaccines are dangerous and can cause particularly fast-growing cancer, but there isn’t evidence that this phenomenon is real. 

The recent study, published May 1 in Frontiers in Oncology, describes one mouse that died from lymphoma out of 14 mice that were given a high dose of the Pfizer/BioNTech vaccine delivered into their veins, which is not how the COVID-19 vaccines are given to people. The study does not show the mouse’s blood cancer was related to the vaccine.

“Our case report in no way attempts to demonstrate a causal relationship between the identified lymphoma and the mRNA vaccine,” Eens said. He added that he and his colleagues have now dosed 70 mice with the vaccine and have seen no further cases of any type of cancer.

Dr. Jason D. Goldman, an infectious disease physician, clinical researcher and epidemiologist at Swedish Medical Center and the University of Washington, emphasized the difficulty of determining whether one event causes another.

“You really can’t tell from a one-off if something has a causal relationship, meaning, does the vaccine cause the cancer? … Cancer happens, and when you vaccinate billions of people, of course many events are going to happen after the vaccines because that’s what happens and it would have happened anyway,” he said. “When we start seeing more patterns is when we think about causality.”

So far, researchers have not seen a larger pattern. “Lastly, we would like to stress that COVID-19 vaccines have demonstrated exceptional safety and efficacy in the fight against the pandemic, and manifestations of serious adverse events after COVID-19 vaccination are very rare,” Eens told us. “To date, there is no scientific evidence of a causal link between mRNA vaccines and cancer development.”