Can mRNA vaccines change your DNA?
Written by AI from saved sources. A script checks every quote word for word, and a second AI compares each claim with its source. How we work and corrections
There is no scientific evidence that COVID-19 vaccine mRNA—protein-making instructions—becomes part of human DNA, our genetic material. A laboratory study reported a vaccine-specific DNA signal; small DNA fragments can remain from manufacturing. Neither finding establishes that material became part of vaccinated people's DNA.
Checked against: European Medicines Agency, Lund University, New Zealand Royal Commission, October 2026.
Why people believe it
There are real findings to ask about: a laboratory DNA signal and leftover DNA. A published human case also claimed integration—material becoming part of someone's DNA. KFF's 2025 poll of US adults linked belief in the DNA-change claim with concerns about COVID-19 vaccine safety. That link does not explain any individual's reasons. Let's take the findings seriously and ask what each shows.
“They turned vaccine mRNA into DNA”
In 2022, Lund University researchers exposed a line of laboratory-grown human liver cells to the Pfizer-BioNTech COVID-19 vaccine. They detected a DNA sequence specific to the vaccine. They saw this as mRNA being copied into DNA as early as six hours after exposure. But in Lund University's Q&A, an author said the study had not investigated whether the Pfizer vaccine changed human genetic material. A scientist commenting in Science Feedback said the study gave no evidence that the material became part of the cells' DNA.
Thinking tool: a cell dish is not a body
These cells came from a liver tumour. A study author warned that they differ from cells in living things. The author also warned that these cells are more genetically unstable than normal human liver cells. Detecting a sequence did not show that it had become part of the cells' DNA. For other claims, ask: what was measured, in what setting, and does the conclusion go further?
“There is leftover DNA in the vaccine”
Yes: DNA provides the pattern for making mRNA. It is then broken down and removed, but small fragments can remain. A 2023 preprint reported excessive amounts with one test but amounts below guidance with another, according to Science Feedback.
In 2025, researchers used four methods to test 15 batches of Comirnaty and Spikevax. They found leftover DNA below approved limits in all 15 batches. 11 batches were expired. They showed that excess RNA can distort DNA tests that use glowing dyes. They warned that purification, or cleaning, also loses some DNA. These tests measured vaccine contents. They did not show that material became part of people's DNA.
“A human case already proves it”
The authors of a 2025 case report claimed integration in one woman with bladder cancer after Moderna vaccination. They analysed tumour DNA circulating in blood, RNA in blood, and proteins in urine. The authors acknowledged that one case cannot establish cause. They called for checks that read longer stretches of DNA, and for larger studies. Voices for Vaccines rejected it as proof. Its public assessment was not an experiment to repeat the study.
“Protein months later means DNA changed”
Researchers in a 2023 study reported a spike-protein fragment linked to the vaccine in half the samples from 20 people. These people had received mRNA COVID-19 vaccines. The fragment was detected 69–187 days after vaccination. Samples from unvaccinated people used for comparison were negative. The researchers proposed integration as one possible explanation. But they explicitly limited their observations to detecting protein.
Official positions, with dates
The US FDA's 14 December 2023 letter said no safety concerns related to leftover DNA had been identified. This was after over a billion mRNA COVID-19 vaccine doses.
The European Medicines Agency's page has DNA updates dated 8 April 2026. It says the agency has seen no evidence linking leftover DNA to side effects. New Zealand's Royal Commission concluded in 2026 that no scientific evidence showed COVID-19 vaccine mRNA becoming part of human DNA. It also described how integration could theoretically happen during repair of a break in both DNA strands. The broken ends would be joined. A DNA fragment would need to be at exactly the break site and repair time. It called these conditions highly improbable.
“What about SV40?”
The FDA's December 2023 letter said mRNA COVID-19 vaccines contain no SV40 proteins and no instructions to make them. Science Feedback had reproduced Health Canada's response by 28 October 2023. The response distinguished the leftover SV40 promoter-enhancer DNA sequence in the Pfizer-BioNTech COVID-19 vaccine from the whole virus. It described the fragment as inactive.
What people also ask
What does mRNA do with DNA?
EMA says cells use mRNA from COVID-19 vaccines to make proteins outside the nucleus, where our DNA is kept. It says the mRNA does not enter the nucleus.
Do mRNA vaccines leave your body?
EMA says cells break down the mRNA in COVID-19 vaccines.
What is the main purpose of an mRNA vaccine?
For mRNA COVID-19 vaccines, EMA describes mRNA as instructions for making protein. It also describes immune cells carrying mRNA to nearby lymph nodes to trigger an immune response.
Why do people worry about mRNA vaccines?
KFF linked US adults' belief in the DNA-change claim with negative views of COVID-19 vaccine safety. This does not establish what caused those worries.
Check it yourself (5 minutes)
- Open Lund University's “Q&A: COVID-19 vaccine study gains attention” (2022).
- Find “What did your study conclude?”
- Read the answer. Did the study investigate whether vaccination alters our genetic material?
What you should have found
The answer says the study “does not investigate whether the Pfizer vaccine alters our genome.”
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