Fluorescence light micrograph of human salivary glands (outlined in green) infected with SARS-CoV-2 virus particles. The genetic material, RNA (ribonucleic acid), from the virus is labelled pink. Angiotensin-converting enzyme 2 (ACE2) receptors, which the virus uses to enter human cells, are white. SARS-CoV-2 causes the respiratory infection Covid-19, which can lead to fatal pneumonia. Prior to March 2021 it was not known that the virus could infect salivary cells. The finding could help explain some of the symptoms of Covid-19, such as loss of taste and dry mouth. Infected oral cells could also play a role in transmitting the virus within and outside the body.