Cancer Patients on Immunotherapy Experience Dramatically Higher Survival After COVID Vaccination

Last updated on 10 DEC 2025

Scientists stumbled upon an unexpected connection while analyzing patient records at a Texas cancer center. Cancer patients who happened to receive COVID-19 vaccines around the time they started a particular type of treatment were living longer. Much longer. Nearly twice as long in some cases. Nobody was looking for it. Nobody predicted it. Yet the data showed something remarkable about those small mRNA shots designed to fight a virus. Research teams at the University of Texas MD Anderson Cancer Center and the University of Florida examined records from more than 1,000 cancer patients treated between August 2019 and August 2023. Patients receiving immune checkpoint inhibitors alongside mRNA COVID vaccines within 100 days showed dramatic survival improvements. At three years, these vaccinated patients were twice as likely to still be alive. Even more striking, patients with the hardest-to-treat cancers saw benefits approaching five times better survival rates. Results appeared at the European Society for Medical Oncology Congress 2025 and in the journal Nature. Researchers now face a question with profound implications for millions of cancer patients worldwide. Could a widely available vaccine designed for an infectious disease also help fight cancer?

Two Cancer Types Show Remarkable Results

Lung cancer and melanoma patients provided the clearest evidence of this phenomenon. Among 180 non-small cell lung cancer patients who received an mRNA vaccine within 100 days of starting immunotherapy, median survival reached 37.3 months. For the 704 patients who remained unvaccinated, median survival was 20.6 months. At the three-year mark, 56% of vaccinated patients were still alive compared to just 31% of unvaccinated patients. Melanoma results proved even more dramatic. Researchers tracked 43 vaccinated patients with metastatic melanoma and 167 unvaccinated patients. Unvaccinated patients had a median survival of 26.7 months, with 44% alive at three years. Vaccinated patients did so well that researchers couldn’t calculate a median survival time because most remained alive. Their three-year survival rate hit 68%. Both Pfizer and Moderna vaccines produced similar results. The number of doses mattered less than timing. Patients who got their shots within that 100-day window around treatment start saw the benefits, whether they received one dose or multiple doses. Researchers controlled for 39 different factors that could influence survival, including cancer stage, mutation status, steroid use, other health conditions, and treatment year. Even after accounting for all these variables, the survival advantage held.

“Cold” Tumors Respond Where Nothing Else Worked

Perhaps the most exciting finding emerged in patients, where doctors often struggle to help. Some cancers create what specialists call immunologically “cold” tumors. Unlike “hot” tumors that trigger immune responses, cold tumors fly under the radar. Immune cells ignore them. Standard immunotherapy often fails against these cancers. Patients with cold tumors typically have low levels of a protein called PD-L1 on their cancer cells. In lung cancer patients with PD-L1 scores below 1%, immunotherapy usually provides minimal benefit. Yet when these same patients received mRNA COVID vaccines around the time they started treatment, their outcomes improved to match patients with more responsive tumors. Analysis of cold tumor patients revealed a nearly five-fold improvement in three-year survival for those who got vaccinated. Doctors had found few ways to help this group before. Vaccines appeared to wake up immune systems that had been ignoring cancer entirely. Results spanned multiple cancer types beyond lung cancer and melanoma. Researchers examined 5,317 pathology reports from patients with various cancers treated at MD Anderson between January 2020 and October 2023. Vaccinated patients across this diverse group showed a 37% increase in PD-L1 expression on their tumors compared to unvaccinated patients. Cancer location didn’t matter. Tumor type didn’t matter. If patients received immunotherapy and got an mRNA COVID vaccine within that 100-day window, survival rates improved.

How an Alarm System Kicks Cancer-Fighting Cells Into Gear

Dr. Adam Grippin, a radiation oncology resident at MD Anderson and co-lead author of the study, explained the discovery in plain terms. “This study demonstrates that commercially available mRNA COVID vaccines can train patients’ immune systems to eliminate cancer,” Grippin said. “When combined with immune checkpoint inhibitors, these vaccines produce powerful antitumor immune responses that are associated with massive improvements in survival for patients with cancer.” But how does a vaccine designed to fight a coronavirus help attack cancer cells? Research teams conducted laboratory studies to answer that question. mRNA vaccines work by delivering genetic instructions to cells. Cells read these instructions and produce a small piece of the coronavirus spike protein. Immune systems recognize this protein as foreign and mount a response. Along the way, the vaccines trigger a surge of signaling molecules called type I interferons. Interferons act like alarm bells. When levels spike, immune cells throughout the body snap to attention. Cells that present foreign material to other immune cells become activated. White blood cells called T cells, which can hunt down and destroy threats, get primed for action. Here’s where cancer enters the picture. Once activated, these immune cells don’t just look for coronavirus proteins. They become better at spotting all foreign or abnormal material, including cancer cells. Immune cells that were previously ignoring tumors suddenly start recognizing them as threats. Cancer cells fight back by increasing the production of PD-L1 protein on their surfaces. PD-L1 acts as a shield, telling immune cells to stand down and not attack. Under normal circumstances, this defensive move would work. But patients in the study were also receiving immune checkpoint inhibitors. These drugs specifically block PD-L1 and similar shield proteins. With their defenses disabled, cancer cells become vulnerable to attack by the newly activated immune cells. Laboratory experiments confirmed each step of this process. Animals treated with mRNA vaccines showed increased interferon levels. Their immune cells became more active. Cancer cells in these animals increased PD-L1 expression. When researchers combined vaccines with checkpoint inhibitors, tumors shrank. Studies in healthy human volunteers showed similar immune activation patterns. Blood tests revealed interferon surges 24 hours after vaccination. Immune cells displayed activation markers. The same biological chain reaction observed in mice was happening in people.

From Graduate Research to Game-Changing Discovery

Dr. Adam Grippin first encountered this idea during graduate work at the University of Florida. Under the supervision of Dr. Elias Sayour, Grippin helped develop personalized mRNA vaccines for brain tumors. During that research, he noticed something odd. mRNA vaccines seemed to help immune systems fight tumors even when the vaccines weren’t specifically designed to target cancer cells. Then COVID-19 arrived. Hundreds of millions of people worldwide began receiving mRNA vaccines. For a researcher interested in how mRNA affects cancer immunity, this massive rollout presented an unprecedented opportunity to examine the question in real patients. Now a senior resident at MD Anderson, Grippin partnered with Professor Steven Lin to lead a team through a retrospective analysis. They combed through electronic health records, looking at outcomes for cancer patients who had received COVID-19 vaccines. Patterns emerged quickly. Patients who got vaccinated around the time they started immunotherapy were doing better. Much better. Grippin’s team expanded their analysis, controlling for dozens of factors that might explain the difference. The survival advantage persisted. Preclinical laboratory work provided the biological mechanism. Clinical data provided the real-world evidence. Together, they painted a picture of how mRNA vaccines might boost cancer treatment.

Survival Benefits Span Multiple Cancer Types

Initial findings in lung cancer and melanoma prompted researchers to look broader. Analysis of the tissue-agnostic cohort revealed benefits across diverse cancer types. Breast cancer, prostate cancer, bladder cancer, and others all appeared in the data. Vaccinated patients showed higher PD-L1 scores on their tumors regardless of cancer origin. Patients who received a COVID vaccine within 100 days before their biopsy had PD-L1 scores 24% higher than those who got vaccinated more than 100 days earlier. Compared to never-vaccinated patients, the increase reached 41%. For lung cancer patients, these score increases have practical significance. Doctors use a PD-L1 threshold of 50% to decide whether patients can receive immunotherapy alone or need it combined with chemotherapy. Vaccinated patients were 29% more likely to meet or exceed that 50% threshold. Researchers checked whether other vaccines produced similar effects. Patients who received flu shots or pneumonia vaccines around the time they started immunotherapy showed no survival improvement. Something specific to mRNA vaccines was driving the benefit. Safety data provided reassurance. Vaccinated cancer patients experienced the same mild, temporary side effects seen in healthy people. Fever, fatigue, and sore arms appeared and resolved within days. Immune-related side effects didn’t increase compared to patients receiving immunotherapy alone. No evidence suggested vaccines accelerated cancer growth or spread.

Nobel Prize Technology Finds New Purpose

mRNA vaccine technology earned its creators the 2023 Nobel Prize in Physiology or Medicine. Katalin Karikó and Drew Weissman spent decades developing methods to use synthetic mRNA as medicine. Their work enabled the rapid development of COVID-19 vaccines that saved millions of lives during the pandemic. Now that same technology shows promise for an entirely different application. Commercially available vaccines, already manufactured and distributed worldwide, might serve as immune boosters for cancer patients. No special production needed. No personalized formulation required. No lengthy waiting periods. Grippin emphasized the practical implications. “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,” he said. “We are hopeful that mRNA vaccines could not only improve outcomes for patients being treated with immunotherapies but also bring the benefits of these therapies to patients with treatment-resistant disease.” Co-senior author Dr. Elias Sayour of the University of Florida sees even broader possibilities. “The implications are extraordinary—this could revolutionize the entire field of oncologic care,” Sayour said. “We could design an even better nonspecific vaccine to mobilize and reset the immune response, in a way that could essentially be a universal, off-the-shelf cancer vaccine for all cancer patients.” Research teams are now designing a randomized Phase III clinical trial. Results from that trial will determine whether COVID vaccines should become standard care for patients receiving immunotherapy. Studies funded by the National Cancer Institute, National Institutes of Health, and multiple foundations are exploring whether optimized vaccines specifically designed for cancer treatment could provide even greater benefits.

Patients and Doctors Face New Treatment Timing Questions

Current findings raise immediate practical questions for oncologists and patients. Should doctors coordinate COVID vaccine timing with immunotherapy start dates? Should patients delay or accelerate vaccination based on treatment schedules? Can patients already on immunotherapy still benefit from vaccination? Study data offers some guidance. Benefits appeared strongest when vaccines were given within 100 days of starting immunotherapy, either before or after treatment began. Patients who received vaccines more than 100 days before starting treatment showed less benefit. Patients who never received immunotherapy saw no cancer-related advantage from COVID vaccines. Results apply specifically to immune checkpoint inhibitors, not chemotherapy. Patients who received COVID vaccines around the time they started chemotherapy alone showed no survival improvement. Something about the combination of mRNA vaccines and checkpoint inhibitors creates the benefit. Several important caveats remain. Study findings come from observational data, not a randomized controlled trial. Researchers observed associations between vaccination and improved survival, but they can’t definitively prove that the vaccines caused the improvement. Other unmeasured factors might explain some of the difference. Scientists funded by multiple organizations, including the National Cancer Institute, are working to confirm findings in controlled trials. Until those results arrive, patients should discuss vaccination timing with their oncology teams. Current evidence suggests COVID vaccines are safe for cancer patients on immunotherapy and may provide substantial benefits beyond infection prevention. For now, doctors and patients have access to a potentially powerful tool hiding in plain sight. Those small shots developed in a pandemic may hold keys to helping millions fight cancer.

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