Can mRNA vaccines really treat cancer?

Positive results from a cancer vaccine trial for melanoma have led some anti-vaccine activists to claim that mRNA vaccines actually cause cancer and make people with cancer die sooner.

• The study found a pattern, but it cannot prove vaccines caused worse cancer outcomes.
• Differences between vaccinated and unvaccinated patients may have skewed the results.
• The claim that IgG4 weakens the body’s ability to fight cancer is still unproven.

The study McCullough’s group is talking about looked back at medical records that had already been collected. This type of study can find patterns, but it cannot prove that the vaccines caused the worse outcomes.

The study also did not fully account for other differences between the groups. One example is the healthy vaccinee effect. People who are healthier and have more regular medical care may be more likely to get repeated vaccine doses. People who are very sick, dying, or in hospice care may be less likely to get boosters. That can make the vaccinated and unvaccinated groups look different even when the vaccine is not the reason.

The study also uses a type of antibody called IgG4 as a sign that cancer may be getting worse. But the idea that spike-related IgG4 weakens the immune system’s ability to fight cancer is still a theory. It has not been proven to cause cancer or make cancer outcomes worse.

Lastly, news reports that a personalized mRNA vaccine for melanoma helped keep cancer from coming back in a large clinical trial. The vaccine is made to match the unique mutations in each person’s tumor and trains the immune system to recognize the cancer. This research is exciting, and we must protect vaccine innovations from political whims.