Cancer patients who received mRNA-based COVID-19 vaccines within 100 days of beginning immunotherapy were found to have significantly improved survival rates, according to new research.
In a study of 180 patients with advanced non-small cell lung cancer who received Moderna or Pfizer/BioNTech’s mRNA vaccines, the median survival was 37.33 months — nearly double the 20.6 months observed among 704 unvaccinated patients.
Similarly, among patients with metastatic melanoma — the most aggressive form of skin cancer — half of the 167 unvaccinated patients had died by 26.67 months. In contrast, more than half of the 43 vaccinated patients were still alive, meaning the median survival could not yet be determined.
“The really exciting part of our work is that it points to the possibility that widely available, low-cost vaccines have the potential to dramatically improve the effectiveness of certain immune therapies,” study coauthor Dr. Adam Grippin of The University of Texas MD Anderson Cancer Center in Houston said in a statement.
U.S. Health Secretary Robert F. Kennedy Jr. has questioned the safety and effectiveness of vaccines, including those developed with mRNA technology — a stance that contradicts established scientific evidence.
Previous laboratory studies have shown that mRNA vaccines can enhance the efficacy of cancer drugs like Merck’s Keytruda, an immune checkpoint inhibitor, by prompting cancer cells to produce more of the PD-L1 protein — the very target these drugs are designed to block.
Notably, in the latest research presented at the 2025 European Society for Medical Oncology (ESMO) Congress in Berlin, the greatest survival benefits were seen in patients whose tumors had low PD-L1 expression and were considered less responsive to immunotherapy. These patients showed a nearly five-fold increase in three-year overall survival after receiving an mRNA-based COVID-19 vaccine.
The results held true across variables such as vaccine manufacturer, number of doses, and treatment location, including at MD Anderson Cancer Center.
“We are hopeful that mRNA vaccines could not only improve outcomes for patients being treated with immunotherapies," said Grippin, "but also bring the benefits of these therapies to patients with treatment-resistant disease.”