(HealthDay News) — The prevalence of olfactory dysfunction (OD) and gustatory dysfunction (GD) declines in the three years after COVID-19 infection, according to a research letter published online Nov. 9 in JAMA Otolaryngology-Head & Neck Surgery.

Paolo Boscolo-Rizzo, MD, from the University of Trieste in Italy, and colleagues estimated the three-year prevalence of measured OD and GD associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. One-hundred individuals who tested positive for SARS-CoV-2 were matched with 100 controls recruited from hospital staff who tested negative for SARS-CoV-2. Eighty-eight cases completed all follow-up assessments.

The researchers found that during the acute phase of COVID-19 and at one-, two- and three-year follow-up, the prevalence of self-reported smell or taste dysfunction was 64.8, 31.8, 20.5 and 15.9%, respectively, among cases. The prevalence of OD decreased during follow-up, with frequency of 40.9, 27.3 and 13.6% of one-, two- and three-year evaluations, respectively. Cases were more likely to have OD than controls at two years after infection (27.3 versus 10.2%); however, at three years after COVID-19, no significant excess of OD was identified (13.6 and 10.2%, respectively). At one-, two- and three-year evaluation, the prevalence of GD was 26.1, 13.6 and 11.4%, respectively; at two and three years after COVID-19, there were no differences in GD observed between cases and controls.

“Patients with post-COVID-19 condition exhibiting chemosensory alterations should be reassured that a recovery of olfaction appears to continue over three years after initial infection,” the authors write.

One author disclosed ties to the biopharmaceutical, medical device, and nutrition industries.

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