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No, DNA fragments in COVID-19 vaccines aren't linked to 'major safety concerns' | Fact check

Nate Trela
USA TODAY

The claim: DNA fragments in COVID-19 vaccines are harmful to humans

A March 16 Instagram post (direct link, archive link) shares a news report about a warning issued by the Florida surgeon general of purported risks associated with DNA fragments in COVID-19 mRNA vaccines.

“There Are Major Safety Concerns With Covid Vaccines Amid The Discovery Of Billions Of DNA Fragments In Both Pfizer And Moderna Vaccines,” reads part of the post's caption. It goes on to claim these DNA fragments in the vaccines change healthy cells into cancerous cells and cause “chromosomal instability,” among other reactions.

The post echoes claims made by Dr. Joseph Ladapo, Florida’s surgeon general, and links to news coverage of his statements.

The post was liked more than 2,000 times in less than two weeks.

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Our rating: False

There is no evidence DNA fragments in COVID-19 vaccines pose any risk, according to the Food and Drug Administration and multiple medical experts. Such fragments are often found in vaccines for viruses. Experts say the leftover material does not cause cancer, lacks a way to get into a cell’s nucleus to change it and is found in too small of a quantity to alter a cell's DNA.

Experts say fear of DNA integration defies science

DNA fragments are found in many viral vaccines as an active ingredient or the byproducts of the manufacturing process, according to Children’s Hospital of Philadelphia. Viruses are usually grown in cells, and some fragments can make their way through filtration processes into the finished vaccine.

Ladapo has claimed that DNA fragments in the COVID-19 vaccines could cause "chromosomal instability" or transform healthy cells into cancerous ones through insertional mutagenesis, where a foreign DNA sequence integrates with a host organism's genome.

But Dr. Paul Offit, director of the Vaccine Education Center at the Philadelphia hospital, told USA TODAY there are several reasons why this is not the case.

First, none of the materials used in manufacturing vaccines contain oncogenes, which are genes known to cause cancer, he said. Second, there are only nanograms – or one-billionth of a gram – of DNA fragments left in vaccine shots when they are delivered. Researchers find they need to use micrograms – one-millionth of a gram – of DNA when trying to integrate foreign DNA into another cell.

Cytoplasm, a liquid that fills the inside of a cell, is also hostile to foreign DNA and attacks any that enters the cell, according to the Children's Hospital of Philadelphia. That is if the foreign DNA from the vaccines is able to enter the cell, which is impossible without an access signal to get through the nuclear membrane of the host's DNA. The foreign DNA does not have such an access signal and also lacks the enzyme needed to integrate with the host cell’s DNA, Offit said.

“It is a millionth of the DNA you would need, and it would never get out of the cytoplasm, and even if it did, it’s not an oncogene,” Offit said. “There’s just zero chance of that happening.”

Dr. Taison Bell, a critical care doctor at UVA Health, told USA TODAY people ingest foreign DNA in many different ways without suffering negative consequences. He pointed to a 2013 study in the journal Plos One showing that far larger quantities of foreign DNA end up in the bloodstream from the food people eat.

“There’s a reason we don’t worry about sprouting gills after eating fish,” Bell said in an email.

Fact check: False claim COVID-19 vaccines are linked to 'spike' in cancer cases

The FDA has also weighed in on the topic, sending a letter to Ladapo spelling out why his concerns over DNA contamination are unfounded. The letter makes similar points to those of Offit and Bell. It also highlights the lack of reported adverse effects related to DNA fragments and research that demonstrates there is no evidence of genetic contamination from the vaccines.

"With over a billion doses of the mRNA vaccines administered, no safety concerns related to residual DNA have been identified," Dr. Peter Marks, director of the FDA Center for Biologics Evaluation and Research, wrote in the letter. "Studies have been conducted in animals using the modified mRNA and lipid nanoparticle together that constitute the vaccine, including the minute quantities of residual DNA fragments left over after DNAse treatment during manufacturing, and demonstrate no evidence for genotoxicity from the vaccine.”

The Instagram post points out that the American Cancer Society projects there will be more than 2 million new cases of cancer in the country in 2024. But as USA TODAY previously reported, the organization in no way links the uptick to COVID-19 vaccines. The National Cancer Institute also says mRNA vaccines have not been linked to cancer.

The post further claims the vaccines affect the lungs, brain, heart and injection site. While there have been rare reports of organ issues after vaccination, none have been severe or prominent enough to warrant guidance from the FDA or the Centers for Disease Control and Prevention beyond acknowledgment of the slightly elevated risk of heart inflammation for adolescents and young adults. Injection site reactions beyond the swelling and bruising seen with many vaccines have been rare and benign, resolving within weeks.

Both the FDA and the CDC continue to recommend COVID-19 vaccines as a safe and effective way to combat COVID-19.

USA TODAY reached out to the social media user who shared the claim for comment but did not immediately receive a response.

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