Scientists around the world are racing to develop a vaccine for the novel coronavirus that has killed tens of thousands of people since late December. Dozens of companies and institutions are leading the charge at a record pace, and some already have begun the first phase of clinical trials. Yet researchers continue to warn that it could take at least a year to 18 months before a vaccine is ready for public use—a long time to wait for what many see as the best hope to stem the spread of the SARS-CoV-2 virus, which causes COVID-19.

Most vaccines don’t cure diseases; they prevent you from getting infected in the first place. Vaccines contain the same germ