Loss of smell, or anosmia, is one of the earliest and most commonly reported symptoms of COVID-19. But the mechanisms involved had yet to be clarified. Scientists from the Institut Pasteur, the CNRS, Inserm, Université de Paris and the Paris Public Hospital Network (AP-HP) determined the mechanisms involved in the loss of smell in patients infected with SARS-CoV-2 at different stages of the disease. They discovered that SARS-CoV-2 infects sensory neurons and causes persistent epithelial and olfactory nervous system inflammation.