Patients with cancer who received mRNA-based COVID vaccines within 100 days of starting treatment with widely used immunotherapies were twice as likely to be alive three years after beginning treatment, researchers reported.
Among 180 such patients with advanced non-small cell lung cancer who received an mRNA COVID vaccine from Moderna or Pfizer/BioNTech, the median survival, or the point at which half the patients had died, was 37.33 months. Among 704 cancer patients who did not receive an mRNA COVID shot, median survival was 20.6 months.
Among patients with metastatic melanoma - the most deadly form of skin cancer - half of the 167 patients who did not receive a vaccine had died by 26.67 months. Of the 43 melanoma patients who did receive a vaccine, more than half were still alive and so median survival could not yet be calculated.
“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 publicly questioned the safety and efficacy of vaccines, including those using mRNA technology, contrary to scientific evidence.
In earlier laboratory experiments, researchers had observed that mRNA vaccines improve the effectiveness of cancer drugs such as Merck's Keytruda, known as immune checkpoint inhibitors, in part by inducing the cancer cells to increase production of the same PD-L1 protein that the drugs are designed to recognize and block.
In fact, the survival improvements in the current study were most pronounced in patients with tumors that were not likely to respond well to immunotherapy because of low production of PD-L1. These patients experienced a nearly five-fold improvement in three-year overall survival rates with receipt of a COVID vaccine, researchers reported at the 2025 European Society for Medical Oncology Congress in Berlin.
The findings were consistent even when considering independent factors, such as vaccine manufacturer, number of doses, and when patients received treatment at MD Anderson.
“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.”