The most common symptom of COVID-19 is losing sense of smell or taste and a new study suggests that it takes around 21.6 days to recover from the symptoms in mild cases.

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The reduced or distorted ability to smell during sniffing or eating is also known as olfactory dysfunction. According to the study, published in the Journal of Internal Medicine, the patient-reported prevalence of olfactory dysfunction was 85.9 percent in mild cases of COVID-19. And 4.5 percent in moderate cases and 6.9 percent in severe-to-critical cases. "Olfactory dysfunction is more prevalent in mild COVID-19 forms than in moderate-to-critical forms, and 95 percent of patients recover their sense of smell at 6-months post-infection," said lead author Jerome R. Lechien of Paris Saclay University.

To determine the results, the researchers involved 2,581 patients from 18 European hospitals. The team also found that the average duration of olfactory dysfunction reported by patients was 21.6 days, but nearly one-quarter of affected patients reported that they did not recover their sense of smell 60 days after losing it. Objective clinical evaluations identified olfactory dysfunction in 54.7 percent of mild cases of COVID-19 and 36.6 percent of moderate-to-critical cases of COVID-19. At 60 days and 6 months, 15.3 percent and 4.7 percent of these patients did not objectively recover their sense of smell, respectively. Reports of COVID-19-related olfactory dysfunction describe a sudden onset of olfactory impairment, which may be in the presence or absence of other symptoms.