A reduced sense of smell, or olfactory dysfunction, is one of the most common symptoms of COVID-19.

In a study of 2,581 patients from 18 European hospitals, the patient-reported prevalence of olfactory dysfunction was 85.9% in mild cases of COVID-19, 4.5% in moderate cases, and 6.9% in severe-to-critical cases.

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% of mild cases of COVID-19 and 36.6% of moderate-to-critical cases of COVID-19.

At 60 days and 6 months, 15.3% and 4.7% of these patients did not objectively recover their sense of smell, respectively.

Jerome R. Lechien, MD, PhD, MS, of Paris Saclay University, lead author of the report said:

“Olfactory dysfunction is more prevalent in mild COVID-19 forms than in moderate-to-critical forms, and 95% of patients recover their sense of smell at 6-months post-infection.”

Many people with mild or no obvious symptoms may not realise that they have Covid. Losing a sense of smell is one of the symptoms which according to this research becomes really noticeable for people with mild symptoms.

The main symptoms of coronavirus are:

• a high temperature – this means you feel hot to touch on your chest or back (you do not need to measure your temperature)
• a new, continuous cough – this means coughing a lot for more than an hour, or 3 or more coughing episodes in 24 hours (if you usually have a cough, it may be worse than usual)
• a loss or change to your sense of smell or taste – this means you’ve noticed you cannot smell or taste anything, or things smell or taste different to normal

Most people with coronavirus have at least 1 of these symptoms.

To find out more about the symptoms of Covid and what you should do if you think you have it check out: NHS Inform

This recent study published the Journal of Internal Medicine examined the loss of smell in the prevalence and recovery in patients with varying degrees of severity of COVID-19.