Fact Check-No evidence COVID-19 vaccines cause cancer

A talk show host tied to the conspiracy-theory website Infowars has made multiple false claims in a broadcast to link COVID-19 vaccines with cancer.

Owen Shroyer, who was charged in August for his role in the Jan. 6 Capitol riot (here), streams his show daily on an Infowars platform.

In one October recording, the Texas native told listeners “the vaccines are causing cancer,” before escalating his claim to say United States authorities “knew the vaccines are causing cancer” (here) and (here).


Shroyer began the seven-minute clip with recounting a case of a woman he found online who had tweeted on Sept. 15 about being scared to receive her COVID-19 shot. She tweeted again on Oct. 7 to say she had since been diagnosed with breast cancer.

“I do believe there is a connection,” Shroyer said. “In fact, we know there’s a connection. Just how bad it is, we’re not sure yet.”

He added that the woman was “obviously peer-pressured” into receiving her vaccine, and that authorities were aware she would eventually develop cancer.

Reuters reached out to the woman on Twitter (she did not want to be identified in this piece), who said she had never spoken to anyone from Infowars, and that her cancer diagnosis was unrelated to her vaccination.

“I haven’t been in contact with anyone from their team,” she told Reuters via Twitter direct message. “I wasn’t peer pressured to get the vaccine. To assume this just because I was worried of possible (short term) side effects is ridiculous. My cancer has nothing to do with any vaccine and I will get the booster shot as soon as my doctors recommend this.”

The woman added: “If the journalists had scrolled through my answers, they would have been aware that I wasn’t peer pressured.”


Using the same case study from Twitter, Shroyer said: “So, three weeks after she gets the COVID vaccine, she gets breast cancer… This is not the only story. This is just one I found today.

“I actually know people personally that got the vaccine and then within two weeks got diagnosed with cancer.”

A spokesperson from the University of Oxford’s Vaccine Knowledge Project (VKP) ( told Reuters this claim reveals a misunderstanding of how fast cancer can develop in the body.

“In order to be detectable at the time of diagnosis, most cancers have already been in existence for months – e.g., breast cancer via a mammogram or prostate cancer via a PSA screening test,” they said. “So, in the case in this video, it is impossible for her cancer to have been ‘caused’ by the vaccine.”

Moreover, there has been no cause-and-effect relationship found between vaccines and cancer, the spokesperson said – meaning diagnoses shortly after vaccination are coincidental.

“One in two people will get cancer in their lifetimes, with incidence increasing with age, therefore, statistically, some people will unfortunately be diagnosed soon after their vaccination.”

The VKP spokesperson added that if a person develops a cancer that requires treatment – such as chemotherapy, which can suppress the immune system – they will become more vulnerable to COVID-19. Therefore, “prior vaccination is even more important”. 


According to Shroyer, the U.S. Centers for Disease Control and Prevention (CDC) and vaccine manufacturers told people to wait until “months or years” after their shots to get a cancer screening.

He claimed: “[Authorities said] don’t get a cancer screening after the vaccine because it’ll show up that you have cancer, but it’ll be a false positive.

“But now people are getting cancer screenings after the vaccine – it’s showing up as cancer and they’re not saying it’s a false positive. So, they knew the vaccines are causing cancer.”

This is not true.

The CDC recommends patients consult their doctors on the best time to receive a mammogram, a specific type of X-ray that detects signs of breast cancer.

It notes that some experts say it best to either have a mammogram before vaccination or waiting four to six weeks afterwards (here).

This is because COVID-19 vaccines can cause a temporary swelling of the lymph nodes under the arm (here and here), which could be a symptom of cancer but could also be a normal reaction to inoculation.


False. There is no evidence that COVID-19 vaccines cause cancer. The video host presented multiple false claims to make an unfounded link between the two.

This article was produced by the Reuters Fact Check team. Read more about our fact-checking work here.