The population’s immunity to SARS-CoV-2, achieved either through infection or vaccination, is crucial to overcome the COVID-19 pandemic. A team of researchers led by the University of Zurich (UZH) has now discovered another component that contributes to SARS-CoV-2 immunity—previous antibody responses to other, harmless coronaviruses. “People who have had strong immune responses to other human coronaviruses also have some protection against SARS-CoV-2 infection,” says Alexandra Trkola, head of the Institute of Medical Virology at UZH.