New research suggests Pfizer and Moderna’s mRNA COVID-19 vaccines could offer an unexpected boost for some cancer patients. A study has found that people with advanced lung or skin cancer lived significantly longer if they received an mRNA COVID-19 vaccine within 100 days of starting immunotherapy. Researchers say it’s not about protection from the virus — it’s about the mRNA molecule itself, which seems to “activate” the immune system and help cancer drugs work better.