One of the key questions in predicting the course of the COVID-19 pandemic is how well and for how long the immune response to the virus protects people from reinfection. The Robb group modelled early SARS-CoV-2 infection and fatality data from different regions around the world to predict how many reinfection cases would be expected if there was no immunity to the disease. Numerous serological studies now support the conclusion that short-term immunity to the virus exists. doi:10.2196/21168