Claims that Pfizer admitted its COVID-19 vaccine causes cancer have circulated online. Here’s what the available evidence actually shows about the vaccine, cancer claims, and DNA-contamination concerns.

Pfizer Admits Its COVID-19 Vaccine Causes Cancer? Here’s What the Evidence Says

A headline claiming that “Pfizer admits its COVID-19 vaccines cause cancer” is highly misleading.

There have been ongoing debates about residual DNA, vaccine testing, and isolated reports of cancer occurring after vaccination. However, Pfizer has not admitted that its COVID-19 vaccine causes cancer. Pfizer states that no evidence has shown its vaccine to cause DNA mutations or vaccine-induced cancer.

The U.S. National Cancer Institute likewise says there is no evidence that COVID-19 vaccines cause cancer, cancer recurrence, or cancer progression.

Where Did the Claim Come From?

Some online stories focus on concerns about tiny amounts of residual DNA that can remain from the manufacturing process of biological medicines. Other claims point to studies that reported different measurements of DNA fragments in vaccine samples.

But finding DNA fragments—or debating how they should be measured—is not the same thing as demonstrating that the vaccine causes cancer. A fact-check of one widely circulated study found that the study itself did not investigate or establish that the Pfizer vaccine causes cancer.

What About “Turbo Cancer”?

Another recurring claim is that COVID-19 vaccines cause unusually aggressive “turbo cancers.” Current evidence does not establish such a phenomenon as being caused by vaccination. Reports of cancer occurring after vaccination cannot, by themselves, demonstrate causation.

What Is Actually Established?

COVID-19 vaccines do have recognized adverse effects, and regulators continue to monitor their safety. For example, the FDA updated the labeling for Pfizer’s Comirnaty and Moderna’s mRNA vaccine in 2025 to include information about the risk of myocarditis and pericarditis.

But cancer is not established as a proven adverse effect of the Pfizer COVID-19 vaccine based on the evidence currently available.

So before sharing a headline saying “Pfizer admits its vaccine causes cancer,” it’s important to distinguish between a scientific concern being investigated, a reported event occurring after vaccination, and evidence demonstrating that the vaccine actually caused the disease.