October 23, 2025 :A surprising twist in cancer research suggests that the widely used mRNA COVID-19 vaccines — namely those from Pfizer‑BioNTech and Moderna — might be doing more than protecting against SARS-CoV-2. According to preliminary findings published in Nature, certain cancer patients who received these vaccines in close proximity to their immunotherapy treatment showed significantly better survival than those who did not.
Researchers from the MD Anderson Cancer Center and the University of Florida analysed nearly 1,000 patients with advanced lung or skin cancers undergoing checkpoint-inhibitor immunotherapy. Their key finding: those who received an mRNA COVID-19 vaccine within 100 days of starting immunotherapy had markedly longer survival compared to those who skipped vaccination. For example, a three-year survival rate for one of the lung cancer cohorts was ~55.7% in the vaccinated group versus ~30.8% in the unvaccinated group.
How it might work
The hypothesis is that the mRNA vaccine acts as a “general immune amplifier” or “siren” that alerts and primes immune cells throughout the body — not just for viral defense, but also for detecting tumour cells. As Dr. Adam Grippin of MD Anderson put it:
“We’re sensitizing immune-resistant tumours to immune therapy.”
Checkpoint inhibitor therapies (like PD-1 or CTLA-4 blockers) are designed to “take the brakes off” the immune system, enabling it to attack cancer cells. The study’s findings suggest that if the immune system is already activated by a vaccine, the effect of the immunotherapy may be enhanced.
What the data show
- Patients with advanced lung or skin cancers who got an mRNA vaccine ≤100 days after starting immunotherapy out-lived their non-vaccinated counterparts.
- The benefit appeared specific to mRNA vaccines; other vaccine types or infections didn’t show the same effect.
- The effect was not about the vaccine preventing COVID-19 infections in those patients, but rather an immune-modulating effect that improved cancer outcomes.
What this means
- This opens a potential new frontier where existing vaccines (designed for infection) might be repurposed or timed strategically to improve cancer treatment outcomes.
- It suggests a synergy between mRNA vaccine technology and oncology — prompting interest in developing mRNA-based cancer vaccines or combining vaccines with immunotherapy.
- It provides a reason for oncologists to reconsider the timing of vaccination in relation to immunotherapy, potentially optimizing when to vaccinate for maximal benefit.
Crucial caveats
- This is preliminary data, not yet a randomized controlled trial. While the results are compelling, they need validation.
- The benefit was seen in certain cancers (lung, skin) and certain treatments (checkpoint inhibitors), so it cannot be generalized to all cancer types or therapies yet.
- It’s important that patients do not stop or delay critical cancer treatments on the assumption that vaccination alone will suffice — the vaccine is an enhancer, not a substitute for proven therapy.
- The study does not suggest that vaccines cause tumour regression on their own; rather they may augment existing immunotherapies.
Expert comment
Oncologists are cautiously optimistic. One said:
“If we can show in a proper trial that an mRNA jab improves responses to checkpoint inhibitors, this could rapidly impact how we treat advanced cancers.”
Cancer researchers see this as a bridge between immunology, virology, and oncology. The same technology that underpinned the rapid COVID-19 vaccine rollout may now play a role in cancer care.
Take-home for patients
- If you have cancer and are eligible for a COVID-19 vaccine, talk to your oncologist about timing — especially if you are starting immunotherapy.
- Vaccination remains safe for most cancer patients and does not reduce the efficacy of cancer treatments. (See guidance from institutions like the National Cancer Institute.
- While the idea of vaccines aiding cancer therapy is exciting, don’t rely solely on this. Standard cancer care (surgery, chemo, immunotherapy) remains foundational.
Summary
Preliminary research shows that mRNA COVID-19 vaccines may boost the effectiveness of immunotherapy in some cancer patients, leading to improved survival — heralding a novel role for vaccine technology in oncology.