Doctors have reported that partial or total loss of the sense of smell is often an early symptom of infection with SARS-CoV-2, the virus that causes COVID-19. Now, researchers reporting in ACS Chemical Neuroscience have shown that in mice, two proteins required for SARS-CoV-2 entry are produced by cells of the nasal cavity that contribute to odor detection. Moreover, larger amounts of the proteins are made in older animals than in younger ones.