A nurse prepares the Pfizer-BioNTech Covid-19 vaccine for children for distribution in Montreal, Quebec on November 24, 2021 ( AFP / Andrej Ivanov)

Covid vaccinated do not 'shed' mRNA to unvaccinated

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A US cardiologist claims in an interview spreading across social media that people who have received the Covid-19 vaccine could pass on messenger RNA (mRNA) to the unvaccinated through close contact, causing harm. This is false; the shots approved in the US and Canada do not contain live, weakened versions of the coronavirus, and the studies referenced in the video do not prove the jabs pose a threat.

"If your (sic) unvaccinated, see this update on the potential threats to you from those mRNA vaccinated via shedding," says a November 30, 2022 Instagram post sharing footage of Peter McCullough, a cardiologist from the US state of Texas whom AFP has previously fact-checked.

The clip is from a nearly 90-minute interview McCullough gave to Tanya Gaw, founder of Action4Canada, a group that has filed lawsuits opposing measures taken by the Canadian government to mitigate the spread of Covid-19.

In the video, McCullough says: "It looks like the messenger RNA is transferring from the vaccinated to the unvaccinated."

Screenshot of an Instagram post taken on December 12, 2022

McCullough has become a fixture in circles opposing the Covid-19 vaccines since his 2021 testimony before the Texas Senate, during which he claimed "there's no scientific rationale" for healthy people under the age of 50 to receive a shot -- false comments that may cost him his board certification.

McCullough told Action4Canada that individuals could "inadvertently" receive a vaccine through kissing, sexual contact or breastfeeding. He advised people to wait 90 days before initiating this kind of contact with someone who is vaccinated.

Clips from the interview spread across Instagram, Facebook and Twitter -- pushed in part by LifeSiteNews, a Canada-based Catholic website whose Facebook page was permanently banned for spreading misinformation. The interview was also translated into Portuguese on the video-sharing website Rumble.

However, medical experts say McCullough's claims are inaccurate.

"The vaccines don't replicate and there is not enough shedding of the vaccine mRNA anywhere for there to be any effect on a partner," said Rachel Presti, medical director of the Infectious Disease Clinical Research Unit at the Washington University School of Medicine, in St Louis, Missouri, in a December 7 email.


In the interview shared online, McCullough references an October 2022 paper from French researcher Helene Banoun to claim mRNA can transfer from the vaccinated to the unvaccinated. AFP debunked a similar claim in 2021.

The study was published by TMR Publishing Group, which appears on Beall's List of potentially predatory journals. It says: "There are numerous reports of non-vaccinated persons who experienced symptoms identical to the adverse effects of the vaccine after having been in contact with freshly vaccinated persons."

The paper goes on to say there were excess deaths in non-vaccinated age groups when vaccination campaigns began, which "could be explained by a phenomenon of transmission of the vaccine or its products."

But there is no indication excess deaths -- the difference between observed and expected death numbers in specific time periods -- recorded in Canada or the US in 2021 or 2022 are related to Covid-19 vaccines. AFP has debunked a similar claim. Health authorities have found only rare serious adverse effects from the shots.

Additionally, Banoun urged caution, saying in an interview about the paper that this type of transmission is "only hypothesis" and that further study is needed.

The US Centers for Disease Control and Prevention (CDC) says on its website: "Vaccine shedding is the release or discharge of any of the vaccine components in or outside of the body and can only occur when a vaccine contains a live weakened version of the virus."

This is not the case for any of the Covid-19 shots authorized in the US and Canada.

Health Canada says on its website that the AstraZeneca and Johnson & Johnson vaccines "use a harmless virus (in this case, the adenovirus) as a delivery system" for the coronavirus spike protein, which helps the body build immunity.

The Pfizer-BioNTech and Moderna shots, on the other hand, use mRNA technology to inoculate recipients against the coronavirus. The vaccines introduce a "blueprint" of the virus's spike protein, which the body can then recognize and fight off if infected.

Dasantila Golemi-Kotra, a microbiologist at York University, told AFP in 2021: "No spike protein gets shed when we get vaccinated."

She added that "even if the spike protein was shedding, although impossible, this protein cannot infect someone else."

Spike protein degrades

McCullough also claims in the video that mRNA has "never been demonstrated to actually leave the body."

"They look like they're permanent, as well as the spike protein that's produced after them," he says.

But Washington University's Presti, an infectious disease physician and researcher, said this is not accurate.

"mRNA degrades fairly rapidly, and is not detectable within a few days," she said. "The spike protein that is made may last longer, but what we were demonstrating was that the immune response continues in the lymph node for a long time, not that the spike protein lasts."

She said in the case of Covid-19 vaccination or infection -- when far more spike proteins are produced -- they are "eventually cleared from the body and broken down to make other proteins."

The CDC says on its website: "After the body produces an immune response, it discards all the vaccine ingredients just as it would discard any information that cells no longer need."

Spike protein in breastmilk

Referencing a September 2022 study, McCullough also claims in the interview that mRNA "is in the breast milk of ill-advised women who took the vaccine during pregnancy or afterwards."

Nazeeh Hanna, chief of the Division of Neonatology at New York University Langone Hospital-Long Island and lead author of the paper published in JAMA Pediatrics, told AFP that is misleading.

"I can tell you this right now, I believe it is safe to breastfeed," he said December 8.

His study did not look at the impact of vaccination during pregnancy -- which other experts have told AFP is safe and effective -- but rather at the milk of lactating individuals who were vaccinated after a baby was born. The paper found that mRNA is present for up to 48 hours in expressed milk, and that it will be passed to the baby intact instead of digested.

Hanna said that because the CDC has not recommended Covid-19 shots for children younger than six months of age, more study is needed to determine whether breastfeeding should be paused for 48 hours following vaccination.

"The risk looks very, very small, but we cannot say it's zero either," he said.

For lactating individuals with doubts, Hanna said the "remedy is simple" - stop breastfeeding for 48 hours post-shot until mRNA vaccines are approved for infants or more studies are concluded.

He said that recommendation only applies to feeding children younger than six months of age -- and that using the study to claim vaccination is dangerous at all stages of breastfeeding is "true deception."

More of AFP's reporting on vaccine misinformation is available here.