Decreased sense of smell or olfactory dysfunction is one of the most common symptoms of COVID-19. In a recent study, researchers examined how common the loss of smell is.
In a study of 2,581 patients from 18 European hospitals, olfactory dysfunction was 85.9% in mild cases of COVID-19, 4.5% in mild cases, and 6.9% in severe and critical cases. The median duration of olfactory dysfunction reported by patients was 21.6 days, but nearly a quarter of affected patients reported that they did not recover their sense of smell 60 days after losing it.
Objective clinical studies have identified olfactory dysfunction in 54.7% of mild COVID-19 cases and 36.6% of moderate to critical COVID-19 cases. After 60 days and 6 months, 15.3% and 4.7% of these patients did not objectively recover their sense of smell, respectively.
Olfactory dysfunction is more common in milder forms of COVID-19 than in mild to severe forms, and 95% of patients regain their sense of smell 6 months after infection, said study lead author Jerome R. Lechien, M.D. Ph.D., MS, Saclay University of Paris.