Scientists Study COVID-19 Shots as Possible Addition to Cancer Treatment

A preliminary study found that people receiving immunotherapy for lung cancer or melanoma lived longer if they had received one of the mRNA vaccines

Liz Szabo,

AARP

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En español

Published December 18, 2025

Alyah Holmes

Some COVID-19 shots may be doing more than preventing a bad cough and fever.

Researchers are exploring whether mRNA vaccines designed to fight the coronavirus could help extend survival for people with advanced cancer who are receiving immunotherapy, a type of treatment that leverages the immune system to better fight cancer. Immunotherapy has shown particular success against lung cancer, kidney tumors and melanoma.

Before the first immunotherapy drugs were approved, in 2011, only 10 percent of people with melanoma lived for five years or more; today, more than half do. Lung cancer survival has also improved, climbing from 18 percent to about 30 percent over the past eight years.

Still, immunotherapy doesn’t work for everyone. Across all cancer types, only 20 to 40 percent of patients respond to this type of treatment. This has led researchers to look for ways to help more people benefit from the treatment.

mRNA vaccines ‘wake up the immune cells’

One promising field of study involves therapeutic cancer vaccines. Unlike shots that prevent people from being infected with measles or influenza viruses, therapeutic vaccines for cancer are designed to train the immune system to fight tumors.

Some of the cancer vaccines in development are personalized for each patient, using tissues from their tumors. Scientists include proteins from an individual’s tumor cells to design the vaccine, which takes one to two months to produce, in the hope of teaching the immune system to identify cancer cells as the enemy and destroy them. Other cancer vaccines train the immune system to target proteins that are shared across many kinds of cancers.

Long before the COVID-19 vaccine was developed, cancer scientists began trying to create therapeutic vaccines using mRNA, or messenger RNA, which carries the genetic information needed to produce proteins.

Scientists at the University of Florida were working on a therapeutic vaccine for brain tumors in 2016 when they made an interesting observation: Vaccines that used mRNA appeared able to train the immune system to kill tumors, even without using genetic material from the person’s cancer. In the experiments, mRNA vaccines appeared to “sensitize” cancer cells to immunotherapy, allowing the medications to work better, said Dr. Adam Grippin, a radiation oncologist now at the University of Texas MD Anderson Cancer Center in Houston.

“We think that the mRNA vaccine acts like a siren to wake up the immune cells inside the tumor,” Grippin said. “When that happens, those cells start attacking the tumor” from the inside.

A closer look at the COVID-19 vaccines

The pandemic provided researchers with an opportunity to study the effects of COVID-19 vaccines on cancer treatment, Grippin said.

He and his team examined the medical records of about 1,000 people with advanced melanoma or lung cancer receiving immunotherapy between Aug. 2019 and Aug. 2023. Scientists noted which people received COVID-19 shots and how long they survived compared with similar patients who weren’t vaccinated.

“We found that those who happened to receive a COVID vaccine lived significantly longer than those who did not receive that vaccine,” Grippin said.

About 56 percent of people with lung cancer who received COVID-19 vaccines during the first 100 days of beginning immunotherapy treatment survived at least three years, compared with 31 percent of those who weren’t vaccinated, according to a study published in Nature in October. Among people with melanoma, 68 percent of vaccinated people survived at least three years, compared with 44 percent of those who weren’t vaccinated.

Researchers found that survival rates increased regardless of whether patients received the Pfizer or Moderna COVID-19 vaccines. Study participants lived longer only if they received an mRNA vaccine.

People who received flu or pneumonia vaccines while in treatment did not live longer than other patients. That leads Grippin and his colleagues to suspect that only vaccines made with mRNA help fight cancer.

Research continues

While the study’s findings are provocative, they don’t prove that COVID-19 shots caused people with cancer to live longer, said Stephanie Dougan, an associate professor of cancer immunology and virology at Dana-Farber Cancer Institute and at Harvard Medical School.

This kind of retrospective study — in which researchers look back at patient records and outcomes — can’t prove cause and effect, Dougan said. That’s because it’s possible that people who chose to get COVID-19 vaccines are different from other patients in ways that affect their survival. For example, it’s possible that people who received a COVID-19 shot had better access to health care, which tends to extend survival from cancer.

The new study “is very exciting, and lots of people in the field are cautiously optimistic,” said Dougan, who researches ways to stimulate the immune system to fight cancer. “It’s certainly worth testing. But we don’t want people to be misled and think, This is going to cure my cancer.”

The new study doesn’t mention which study participants actually got COVID-19, Dougan said. COVID-19 infections can cause harm throughout the body, which may have left the unvaccinated patients less able to survive cancer. In particular, COVID-19 can damage the lungs, which could affect the survival of people with lung cancer.

So it’s possible that the most important factor in surviving cancer in the study was avoiding COVID-19 infection, not receiving an injection of mRNA, Dougan said.

Additional factors could have affected whether study participants were vaccinated against COVID-19, says Dr. Mark Yarchoan, associate professor of oncology at the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins.

“I can tell you, as someone who sees patients, the patients who get COVID vaccines are different from the patients who don’t get COVID vaccines,” said Yarchoan, who also researches cancer vaccines. “For example, the patients who didn’t get COVID vaccines might have skepticism about the medical establishment in general, and that could lead to this group having poorer outcomes.”

While it’s possible that an mRNA vaccine could “activate the immune system in a way that could be beneficial in cancer,” people should read the study with “a healthy dose of skepticism” until these findings are confirmed in a large clinical trial, Yarchoan said.

Grippin and his colleagues are planning a definitive clinical trial, in which people receiving immunotherapy for cancer will be randomly assigned to get a COVID-19 shot or not.

In the meantime, doctors say people with cancer should continue to be vaccinated against COVID-19, flu and other respiratory diseases that can reduce their chances of survival.

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