DNA Contamination in Vaccines: What Is It and Why Does It Matter?

Controversy over DNA contamination in vaccines has been making headlines lately. CHD Senior Research Scientist Karl Jablonowski explains what it is, how it happens, and why it raises health concerns.

by Brenda Baletti, Ph.D.

Legacy media fact-checkers and regulators across the world repeatedly claim that DNA contamination in vaccines — and particularly in the mRNA COVID-19 vaccines — poses no risk to vaccine recipients.

Some have gone so far as to claim that concerns raised about this issue by countless researchers are “baseless,” “misinformation” and “conspiracy theory.”

They concede that both older vaccines and the newer mRNA vaccines can contain residual DNA leftover from the manufacturing process — but say that remnant DNA is “expected and considered safe” and that there are regulatory steps in place to make sure it occurs only in limited quantities.

The U.S. Food and Drug Administration (FDA) dismissed concerns published in the Journal of Inorganic Biochemistry about HPV (human papillomavirus) DNA fragments found in products like Merck’s Gardasil HPV vaccine. The agency claims the fragments are “not contaminants” and not a risk or a safety factor.

The Australian Therapeutic Goods Administration last month issued a statement saying that recent studies claiming mRNA vaccines are contaminated with excessive levels of DNA lack scientific rigor and that residual DNA has been in biotech products for a long time anyway.

Australian regulators emphasized that “the benefits of vaccination far outweigh the potential risks.”

But some scientists — including Karl Jablonowski, Ph.D., senior research scientist at Children’s Health Defense, who spoke with The Defender — say residual DNA in vaccines should not be dismissed — the danger he said stems from both known and unknown risks.

Jablonowski said those risks have long been present in many existing vaccines, but they are even greater in the mRNA vaccines. Through the lipid nanoparticles contained in the mRNA shots, the DNA fragments “have an open pass to every membrane in your body.”

Why does DNA contamination happen?

Biology is complex, Jablonowski told The Defender. Nothing in it is very pure, so there are contaminations in everything.

He said there have been problems with contaminants in vaccines since what the journal Pediatrics described as the “First Modern Medical Disaster” — when 13 children administered a contaminated diphtheria antitoxin died.

Today, vaccines are produced in several different ways, but living cells play a part in the manufacturing of most vaccines, Jablonowski explained. Vaccines typically work by introducing a weakened bacteria or virus, or pieces of them — often with an adjuvant to amplify its effect — into the body to trigger an immune response.

Viruses need living cells to grow, so viral vaccines use some kind of living cell in the production process. The viruses can be grown in bacteria, yeast, animal or human fetal cells, for example.

That DNA in those cells is typically destroyed or fragmented in the process of making the vaccine. However, the process might not eliminate all of it — some remnant, fragmented DNA can remain present.

The mRNA COVID-19 vaccines used a different process. Rather than introducing a viral protein, they introduced messenger RNA, which trains cells to produce the SARS-CoV-2 spike protein and the immune system recognizes that protein and produces antibodies.

The COVD-19 vaccines used an RNA-making enzyme — an RNA polymerase — which uses a DNA template to synthesize the RNA in a lab process called “in vitro transcription.”

The DNA used in the process first has to be amplified. Vaccine makers like Pfizer amplified the DNA for the vaccine using a plasmid. Plasmids are small circular pieces of DNA that reside in bacteria and get reproduced when a bacteria reproduces. For the COVID-19 vaccines, they used E. coli, a commonly used bacteria in vaccine production, for rapid amplification.

This DNA template comes with additional risk because the DNA of the plasmid used to create the template has to be removed from the vaccine before it can be injected into people.

Kevin McKernan, the researcher who first identified the DNA in the COVID-19 vaccines, found that the vaccine makers tried to get rid of that DNA by “chewing it up with an enzyme” called deoxyribonuclease or DNase, which breaks down DNA. However, they failed to completely eliminate it.

What are the potential dangers?

The potential risks of residual DNA in vaccines have been debated for decades without resolution, according to the World Health Organization (WHO). Some researchers claim the remnant DNA is inert. Others argue it is an important risk factor that may be oncogenic — cancer-causing — or infectious.

The immune system, a delicate system of sensors, has a threshold for how much foreign material it can tolerate in the body, Jablownoski said. When DNA is present outside of cells and in the bloodstream, it can initiate a powerful immune response — called an interferon response — which will aggressively seek out the harmful pathogen.

This can create an overblown immune system response that could be a vector for autoimmune issues related to vaccine contamination.

For example, pathologist and molecular gene detection expert Sin Hang Lee identified the residual RNA in the HPV vaccine Gardasil, which he tested for fragment DNA after a 13-year-old girl developed acute juvenile rheumatoid arthritis, Maryanne Demasi, Ph.D., reported.

In the Gardasil vaccine, Lee found the HPV DNA present bound tightly to the aluminum adjuvant. As a result it doesn’t easily break down as it should. Lee theorized that immune cells such as macrophages, which are laden with aluminum adjuvant, travel from the injection site through the blood to various organs.

According to Demasi, the HPV DNA that is bound to the adjuvant “can cause chronic immune-inflammatory reactions that lead to autoimmune conditions in some people.”

Jablonowski said the mRNA vaccines pose a new and more serious problem. That’s because before the introduction of the mRNA vaccine, foreign DNA had no mechanism to get inside of a cell. However, the lipid nanoparticles make that possible.

“The appropriate amount of foreign DNA inside the cell is zero,” Jablonowski said. “It can run amuck with all of the delicate biology necessary to operate a cell.”

Foreign DNA could cause cells to become diseased, it can disrupt regulation, and if the DNA is present at cell division, it could get inside the nucleus and create a host of problems, he said.

Some researchers have argued there is evidence this contaminant DNA could be linked to rising cancer rates.

What do the regulators say? 

In 1985, the FDA set an upper limit of 10 picograms per dose. In 1987, the WHO ncreased its recommended limit to 100 picograms and then increased it again to 10 nanograms (i.e., 100 times higher) — a limit now adopted by the FDA, Demasi reported.

Researchers like Lee and McKernan say in the case of Gardasil, this limit doesn’t offer adequate protection, because the HPV DNA can be hard to detect when it binds to the adjuvant.

Jablonowski said when this threshold was set, regulators were only considering how much residual DNA might be in the bloodstream from vaccines — because at that time there wasn’t a mechanism for the DNA to get into the cell. But with mRNA vaccines, that threshold can likely pose a serious danger.

Why did DNA contamination become so controversial? 

Researchers and scientists have had concerns about DNA contaminants in vaccines for decades. However, last year, genomics researcher McKernan reported finding that Pfizer’s COVID-19 vaccine is contaminated with plasmid DNA — which should not be present in an mRNA vaccine.

He said this raises concerns that the plasmid DNA could lead to cancers or autoimmune issues in some vaccine recipients.

After McKernan’s lab made its findings public, and other researchers confirmed them, Health Canada also confirmed that the Pfizer vaccine contains this DNA.

McKernan also reported that Pfizer concealed this information from regulators. In the manufacturing process for the drug’s clinical trials, Pfizer used PCR testing rather than the plasmid DNA it later used for mass production. So the first version of the drug — granted emergency use authorization by the FDA — didn’t contain the DNA.

It was later revealed that the Moderna vaccines used the same production method — so Moderna’s mRNA vaccines also were contaminated with the remnant DNA.

The issue quickly became politicized, with those claiming the vaccines are “safe and effective” calling the claims “misinformation” and a conspiracy theory, dubbed “plasmid-gate.”

Critics of the COVID-19 vaccines, like Florida Surgeon General Joseph A. Ladapo, called on regulators to address the issue.

The FDA said in a response letter that “based on a thorough assessment of the entire manufacturing process, FDA is confident in the quality, safety, and effectiveness of the COVID-19 vaccines.” However, the agency provided none of the evidence on which it based that conclusion.

Dr. Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia, who serves on an FDA advisory committee for the COVID vaccines — and who is himself a vaccine inventor and patent holder on RotaTeq, the rotavirus vaccine recommended for universal use in infants by the Centers for Disease Control and Prevention (CDC) — in a YouTube video dismissed the concerns raised by MeKernan, Ladapo and others.

He said it is possible that there is fragment DNA in the vaccines, but that it is impossible for the DNA fragments to enter people’s cells or to cause disease.

Jablonowski said that for Offit’s explanation to make sense, biology would have to be very simple and straightforward. But it’s not, he said. “Biology is really messy and there are almost always exceptions.”

The immune system is the second-most complicated system, and there is a lot we don’t know about it, he added.