Jan. 7, 2021 -- A European study found patients with mild cases of COVID-19 were much more likely to report losing their sense of smell than patients with moderate to critical cases. Almost all the patients got their sense of smell back within 6 months, the study said.
Researchers questioned and observed 2,581 COVID-19 patients from 18 European hospitals from March to June about olfactory dysfunction (OD), or loss of smell, according to the study published in the Journal of Internal Medicine. OD is one of the most common symptoms of the coronavirus.
Patients reported a loss of smell in 85.9% of mild cases of COVID-19, 4.5% in moderate cases, and 6.9% in severe to critical cases, the study said. A person was judged to have a mild case if there was no evidence of viral pneumonia and they were recovering at home.
Patients reported losing their sense of smell for an average of 21.6 days, but about a quarter of the patients said they didn’t recover it for 60 days.
The researchers also did “objective clinical evaluations” using things like the “sniffin-sticks test.” Researchers observed loss of smell in 54.7% of mild cases and 36.6% of moderate to critical cases, the study said.
“OD is more prevalent in mild COVID‐19 forms than in moderate‐to‐critical forms,” researchers concluded. “OD disappeared in 95% of patients regarding objective olfactory evaluations at 6 months.”
In the 2,581 patients, 2,194 cases were classified as mild, 110 as moderate, and 277 as severe to critical. Patients were classified based on the World Health Organization’s COVID‐19 disease severity scoring.
The ethnicities of the people in the study were Caucasian (83.6%), South American (11.6%), Asian (1.2%), North African (1.2%), Black African (0.7%), and mixing/other (1.5%).
The study found younger patients were more likely to report losing their smell than older patients, but researchers said they didn’t know why.