Vaccines help a person to generate an immune response against an infection without first being exposed to the pathogen. Studies of other coronaviruses, such as the four that cause some common colds, lead most researchers to assume that people who have recovered from COVID-19 infection will be protected from reinfection for a period of time. In a Q&A published in Nature, Michael Diamond, MD, PhD, the Herbert S. Gasser Professor of Medicine, said this assumption needs to be backed by evidence. “We don’t know that much about immunity to this virus,” he said.