Study: Smell, taste loss from COVID-19 can take up to two years to return

Aug. 4 (UPI) -- It took as long as two years, but nearly 9 out of 10 people who reported a loss of smell or taste from mild cases of COVID-19, pre-Omicron, completely recovered, a new study says.

Specifically, 88.2% of patients reporting a COVID-19-related problem with smell or taste had recovered fully within that period, according to a research letter published Thursday in JAMA Otolaryngology-Head & Neck Surgery.

Patients should be reassured that while recovery from smell or taste impairment may continue for many months after the onset of COVID-19, problems eventually will resolve, said the researchers, led by Dr. Paolo Boscolo-Rizzo in the Department of Neurosciences' section of otorhinolaryngology at University of Padova in Treviso, Italy.

Their research paper notes that before COVID-19's Omicron variant emerged, smell and taste dysfunction were among the most commonly reported symptoms of people who were mildly symptomatic from the virus.

Smell and/or taste dysfunction also are symptoms of people experiencing long-term effects from the coronavirus, a condition known as long COVID, researchers said.

They noted that 7% of patients are "functionally anosmic" -- have lost their sense of smell -- one year after SARS-CoV-2 infection.

The scientists cited the importance of estimating the "long-term persistence" of these symptoms, given the huge caseload of COVID-19 during the ongoing global pandemic.

In their previous research, they looked into the prevalence of an altered sense of smell or taste in mildly symptomatic patients at onset, four weeks, eight weeks, and six months after COVID-19, with symptoms assessed using questionnaires.

The same patients were involved in the estimate of the two-year prevalence and recovery rate of smell or taste problems.

The study involved 168 adults, aged 18 years and older. Initially, they were assessed during the acute phase of the disease at Treviso General Hospital and included if they tested positive for SARS-CoV-2 by polymerasechain reaction, or PCR, testing between March 2019 and March 2020.

Among the 119 patients whose onset of COVID-19-associated smell or taste dysfunction occurred within four weeks, 105 of them, or 88.2%, reported complete recovery at two years; 11, or 9.2%, reported a decrease in the severity, and three, or 2.5%, reported the symptom was unchanged or worse.

A late recovery, defined as more than six months after the coronavirus' onset, was reported in 13 patients, or 10.9%.

At the study participants' two-year follow-up, the other most frequently reported post-COVID symptoms were fatigue in 18.5% of them, followed by shortness of breath,10.7%. Some 28% of patients reported the persistence of at least one symptom.

The scientists said the study's results must be interpreted with caution due to several limitations, since smell and taste problems were self-reported and the number of participants was relatively small and geographically limited. Also, patients with more severe symptoms were not included.