Fact Check-COVID-19 vaccines do not add a ‘third strand’ of DNA

Moderna’s mRNA COVID-19 vaccine does not alter human DNA or add a third strand to people’s DNA, as claimed in a video circulating on social media and viewed more than 400,000 times on Twitter.

The brief video makes claims about the religious significance of the order of bonds holding together the double-stranded DNA molecule inside human cells, and references a Moderna Inc patent to suggest that the company’s COVID vaccine has the ability to add a third strand to DNA.

“From the biology side, this isn’t how the vaccines or biology work,” Dr. Tara Kirk Sell, senior scholar at John Hopkins Center for Health Security and associate professor in the Environmental Health and Engineering department at the Johns Hopkins Bloomberg School of Public Health, told Reuters via email. “From the misinformation side, claims like these hook into existing false narratives related to conspiracies and gain a lot of traction though fake science talk.”

The circulating clip is labeled with the TikTok user handle @jaxlovesjesus_, but a search on the platform did not return this profile (

Users have shared the video on Twitter (here) and on Facebook ( with comments such as, “What if the Covid vaccine really is giving us a third strand of DNA? This gave me chills.”

However, the video offers no evidence for its claim about the vaccine altering human DNA. The video includes a brief screenshot of a page from a broad 2020 Moderna patent on its method of synthesizing RNA strands in order to manufacture proteins (here). A circled passage on page 25 of the patent document in the screenshot refers to the possibility of making synthetic RNA that encodes instructions for manufacturing other types of medically useful RNA, including an RNA triple helix formation. The passage does not refer to the mRNA used in the company’s existing COVID-19 vaccine or to DNA.

The messenger RNA (mRNA) in approved COVID-19 vaccines does not interact with human DNA inside cells, and does not enter the cell nucleus where DNA is housed. The vaccine contains synthetic mRNA molecules encoding a version of the coronavirus spike protein. The vaccine mRNA enters the cell’s cytoplasm, where our own cellular machinery will read these instructions and manufacture the spike protein, which our immune system will learn to recognize so it can fight off the coronavirus in the future, as explained in a National Human Genome Research Institute (NHGRI) graphic (here).

Our own cells also manufacture mRNA every day, as illustrated by NHGRI (here). Inside the cell nucleus, the DNA double helix unwinds just enough for a specific gene to be “transcribed” into a single-stranded RNA molecule, which is then edited down into a shorter mRNA version. The mRNA leaves the nucleus to have its message read by cellular machinery in the cytoplasm, which “translates” it into a protein. Once the message has been read, the mRNA molecule quickly breaks down and has no further function.

The U.S. Centers for Disease Control and Prevention and other outlets have previously explained that vaccines do not enter the nucleus of the cell where DNA is located, so they “cannot change or influence our genes” (here) and (here).

Reuters has also addressed other false claims that mRNA vaccines alter human DNA (here, here, here).

Mark Lynas, a visiting fellow at Cornell University’s Alliance for Science group, previously told Reuters (here) that no vaccine can genetically modify human DNA. “That’s just a myth, one often spread intentionally by anti-vaccination activists to deliberately generate confusion and mistrust,” he said.


False. COVID-19 vaccines based on mRNA do not alter human DNA or add a third strand to the DNA double helix.

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