90% of COVID-19 patients recover sense of smell, taste within 4 weeks, study finds

July 2 (UPI) -- Nearly 90 percent of COVID-19 patients who lose their sense of smell or taste or both after becoming infected will see these symptoms begin to resolve within a few weeks, according to a study published Thursday by JAMA Otolaryngology-Head & Neck Surgery.

Even in patients for whom the symptoms remain, or worsen, the lingering effects are not a sign that the new coronavirus, SARS-CoV-2, remains in their system, the researchers said.

"The loss of smell or taste is among the most common and persistent symptoms of COVID-19 in patients with mildly symptomatic disease," the authors wrote.

"However, at four weeks from the onset, most patients reported a complete resolution or improvement of these symptoms," they said.

An earlier analysis by the same team of researchers -- from Treviso Regional Hospital in Italy and St. Thomas Hospital in London -- found that roughly two-thirds of patients with mild COVID-19 lose their sense of smell and/or taste. That finding was based on an assessment of 202 patients treated at Treviso.

For this study, the researchers surveyed the same group of 202 patients in mid-April -- roughly four weeks after they were first diagnosed with COVID-19 -- and asked them about their symptoms and retested them for the virus.

Fifty-five patients -- or nearly 49 percent -- reported complete resolution of their smell and/or taste impairment, while 46 -- or just under 41 percent -- indicated that they had experienced an improvement in symptom severity, the researchers said.

Only 12 -- or less than 11 percent -- reported that their smell/taste deficiencies remained or had worsened, they said.

The duration of smell or taste impairment in recovered patients was approximately 11 days, the researchers said.

However, persistent loss of smell and taste was not necessarily an indicator of the continued presence of SARS-CoV-2, they said.

Of the 58 patients who still were experiencing smell and/or taste deficiencies four weeks after symptom onset, 31 -- or roughly 54 percent -- still tested positive for the virus, compared to 26 -- or just over 46 percent -- of fully recovered patients, the researchers said.

"A higher severity of smell and taste impairment at [onset of infection], reasonably due to a more severe injury ... was associated with a lower likelihood of recovery at four weeks," the authors wrote.