Moderna’s experimental cancer vaccine treats but doesn’t prevent melanoma – a biochemist explains how it works

Media outlets have reported the encouraging findings of clinical trials for a new experimental vaccine developed by the biotech company Moderna to treat an aggressive type of skin cancer called melanoma.

Although this is potentially very good news, it occurred to me that the headlines may be unintentionally misleading. The vaccines most people are familiar with prevent disease, whereas this experimental new skin cancer vaccine treats only patients who are already sick. Why is it called a vaccine if it does not prevent cancer?