Myth that COVID-19 vaccines cause cancer takes hold

Social media and the shift away from legacy news outlets have allowed vaccine opponents to promote false anti-vaccine information to audiences larger than previously imaginable. That is how false claims about cancer-causing DNA in COVID-19 vaccines can take hold in a span of months, while similar myths about other vaccines never gained much mainstream traction in the decades before. 

Vaccine opponents are now using the tactics that successfully sowed hesitancy about COVID-19 vaccines against other routine immunizations. By targeting vulnerable groups like new and expecting parents, anti-vaccine narratives may damage the perception and acceptance of vaccines, leading to a decline in vaccination rates and a rise in vaccine-preventable disease outbreaks.

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Trending narratives from the past month

False claims circulate that DNA in COVID-19 vaccines causes cancer
A recent trending narrative claims that COVID-19 vaccines contain cancer-causing DNA from simian virus 40 (SV40). Some vaccine opponents baselessly claim that SV40 DNA in vaccines causes abnormally aggressive or “turbo” cancer. Some COVID-19 vaccines contain a small fragment of SV40 called the promoter, which cannot induce cancer. False claims about vaccine ingredients can result in harmful narratives that cause hesitancy, like the widely debunked myth that mercury (thimerosal) in MMR vaccines causes autism. Moreover, myths about SV40 in polio vaccines have affected the perception and acceptance of the vaccine worldwide for decades. The latest trending narratives could similarly impact COVID-19 vaccines and others that use the SV40 promoter. Read the fact checks here and here.


Myths persist about COVID-19 vaccine safety during pregnancy
Social media posts seized on two recent studies to cast doubt on the safety of COVID-19 vaccination while pregnant or breastfeeding. A Lancet study found that trace amounts of inactive vaccine mRNA is sometimes detected in breast milk up to two days after COVID-19 vaccination. The study did not find the mRNA to be dangerous and concluded that breastfeeding after COVID-19 vaccination is safe. A second study found a potential association between COVID-19 vaccination and increased abnormal vaginal bleeding in non-menstruating women. This study also found no evidence that the vaccines are harmful. Nonetheless, vaccine opponents continue to claim the studies prove vaccines are unsafe. Safety concerns are among the top reasons pregnant people refuse COVID-19 vaccines and have a lower vaccination uptake than other adult populations. Read the fact checks here and here.


COVID-19 vaccine opponents push broader vaccine opposition
Several viral social media posts advanced the message that a negative perception of COVID-19 vaccines naturally leads to broader anti-vaccine beliefs. The narrative that “I wasn’t an anti-vaxxer until COVID” has gained traction online in the last month, promoted by some prominent COVID-19 opponents. The anti-vaccine movement used false information to skew public opinion of COVID-19 vaccines so successfully that 30 percent of the U.S. population believes COVID-19 vaccines cause sudden deaths, and 20 percent believe it causes infertility. Now, some of the same tactics  are laying the groundwork to discredit all vaccines. Read the fact checks here and here

What to say in response

There is no evidence that COVID-19 vaccines cause cancer. This is an anti-vaccine myth.

  • There is no increase in cancer diagnoses, progression, or deaths after COVID-19 vaccination. “Turbo cancer” is a term coined by vaccine opponents with no basis in medicine.
  • Some COVID-19 vaccines use DNA from a small portion of SV40 but not the full virus. These DNA fragments are harmless, are not biologically capable of inducing cancer, and have been used in medical research for decades. 
  • All vaccine ingredients are thoroughly tested and monitored for safety. Anti-vaccine narratives capitalize on the public’s lack of knowledge about vaccine development to instill fear about harmless vaccine ingredients

Dozens of studies worldwide show that COVID-19 vaccines are safe while pregnant and breastfeeding.

  • COVID-19 infection poses a higher risk of severe illness and hospitalization to pregnant people and infants under 6 months who are too young to receive vaccines, making vaccination during pregnancy particularly important. 
  • Dozens of studies with over 350,000 participants have shown COVID-19 vaccines to be safe during pregnancy.
  • COVID-19 vaccine mRNA is not harmful, and the trace amounts transiently detected in breast milk pose no safety risk.

Vaccines are safe and protect children against deadly and debilitating diseases.

  • All vaccines undergo thorough safety testing before they are approved for the public and are monitored for safety. Few medical interventions are more rigorously scrutinized and have higher safety standards than vaccines.
  • Children are far more likely to be hurt by a vaccine-preventable disease than a vaccine. Hundreds of millions of infants and children safely receive routine immunizations against multiple diseases each year. 
  • False vaccine information fuels vaccine hesitancy, which leads to declining vaccination rates and outbreaks of vaccine-preventable diseases.

What we’re reading

Studies and trainings

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