Fact Check-No evidence spike proteins from COVID-19 vaccines are toxic

There is no proof that spike proteins created in response to mRNA vaccines are harmful to the body, scientists have told Reuters.

The claim was made by immunologist Byram Bridle (here) in an interview on May 28 (here) with Canadian broadcaster Alex Pierson (here and here).

Bridle asked listeners to brace themselves for “scary” findings that he assured were “completely backed up by peer-reviewed scientific publications”. He said: “We made a big mistake… we thought the spike protein was a great target antigen, (but) we never knew the spike protein itself was a toxin and a pathogenic protein.”

He speculated that COVID-19 shots could lead to cardiovascular problems and infertility, because “by vaccinating people we are inadvertently inoculating them with a toxin” (timestamp 8.27).

The claim was repeated online (here , here , here), notably in an article by the Hal Turner radio show (here), a radio programme broadcast by the namesake’s far-right political commentator.

Reuters presented the statement to experts at the Meedan Digital Health Lab (, who responded: “So far, there is no scientific evidence available that suggests spike proteins created in our bodies from the COVID-19 vaccines are toxic or damaging our organs.” (here)

Research shows that spike proteins (here) remain stuck to the cell surface around the injection site and do not travel to other parts of the body via the bloodstream, they added. The 1% of the vaccine that does reach the bloodstream is destroyed by liver enzymes.

Bridle said his findings were corroborated by “cutting-edge science” from Japan’s Pharmaceuticals and Medical Devices Agency (PMDA) (, which he allegedly obtained through a freedom of information request (timestamp 4.41).

Turner’s website repeated the claim and linked this Japanese document as Bridle’s source (here). The article provided no further context, but research conducted by Reuters showed that the chapter was taken from this document (here), which featured the words ‘PFIZER CONFIDENTIAL’ in the footer.

When Reuters presented the document to Pfizer, however, a spokesperson wrote in an email that the file is a Common Technical Document (CTD) unrelated to Bridle’s claim.

Pharmaceutical companies are required to submit CTDs to regulatory authorities in the European Economic Area, Japan and the United States before medicines or vaccines can be approved (here). Pfizer submitted this CTD to be assessed by the PMDA before the shot was certified in February 2021 (here).

“We can confirm the document does not make any reference to spike proteins from the vaccine resulting in dangerous toxins that linger in the body – this claim is incorrect”, the spokesperson said.

Rather, the document detailed early pharmacokinetic laboratory studies (here) that assessed how the vaccine moved through the bodies of mice and rats. The study found expected inflammation associated with an immune response and concluded the shot was safe. No toxins were found in the vaccine.

Bridle also cited another study that - he claimed - found: “A spike protein in circulation in the blood of 11 of those 13 healthcare workers that had received the vaccine.” He said this was “clear cut evidence” that the vaccine leads to blood clots, bleeding, heart problems and brain damage (timestamp 6.18).

The study co-author, David Walt (here), denied this. “Bridle is taking our results and completely misinterpreting them,” he wrote in an email to Reuters.

Walt said the study (here) found tiny concentrations of the spike protein in the first five days following vaccination, which showed that the body was producing the protein as intended.

Crucially, these spike proteins declined in the subsequent weeks, and no spike proteins were detected after the second injection. This is because the individuals developed antibodies to remove the antigen from the bloodstream, creating an immune response exactly as the vaccine was designed to do.

The tiny quantities measured in the bloodstream of vaccinated people were not toxic, Walt explained. By contrast, people who catch the coronavirus and become infected with COVID-19 can develop high levels of the spike protein that can cause adverse effects.

He added: “The most important message is over 400 million doses of the mRNA vaccine have been administered with negligible serious consequences.  It is incredibly safe.”

Scientists online also took to social media to counter Bridle’s claim. This includes pharmacologist Sabina Vohra-Miller (, who produced a Twitter infographic explaining that spike proteins from the vaccine are harmless and do not impact infertility (here).

Reuters contacted Bridle about his claims, who sent an automatic response saying that he was not accepting media engagements, but rejected a “libellous website” and “public smearing campaign” that resulted from his radio interview.


False. Experts say the tiny level of spike protein measured in the bloodstream of vaccinated people does not cause toxicity; rather, they show the vaccine is getting to work. The studies Bridle cited as proof of toxicity do not support his claims.

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