Data presented at ESMO and MD Anderson analyses indicate that administration of mRNA COVID‑19 vaccines near the time of starting checkpoint inhibitors correlates with improved survival in some cancer patients. MD Anderson researchers reported retrospective findings that vaccinated patients receiving immunotherapy within 100 days lived longer than unvaccinated counterparts. A separate institutional analysis observed enhanced checkpoint responses in patients who had recent mRNA vaccination, suggesting an immunologic adjuvant effect in certain contexts. Investigators caution these are observational findings that require prospective validation to rule out confounders. Oncologists and trialists will consider whether vaccine timing should be recorded or stratified in immunotherapy studies and whether prospective trials are warranted to test causal effects on anti‑tumor immunity.