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Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection can cause a wide array of symptoms ranging from mild to severe or fatal forms of coronavirus disease 2019 (COVID-19). Furthermore, it has been observed that in a proportion of patients a variable range of symptoms may persist for a long time. An increasing number of studies have been focused on long COVID, but they have mainly been concentrated on previously hospitalized severe COVID-19 patients reporting symptoms up to 6-months after illness. The main aim of this study was to evaluate the prevalence of COVID-related symptoms 12-months after the onset of mild-to-moderate disease.

Purpose: The aim of the present study was to estimate the 1 year prevalence and recovery rate of self-reported chemosensory dysfunction in a series of subjects with previous mild-to-moderate symptomatic COVID-19. Methods: Prospective study based on the SNOT-22, item “sense of smell or taste” and additional outcomes. Results: 268/315 patients (85.1%) completing the survey at baseline also completed the follow-up interview. The 12 months prevalence of self-reported COVID-19 associated chemosensory dysfunction was 21.3% (95% CI 16.5–26.7%). Of the 187 patients who complained of COVID-19 associated chemosensory dysfunction at baseline, 130 (69.5%; 95% CI 62.4–76.0%) reported complete resolution of smell or taste impairment, 41 (21.9%) reported a decrease in the severity, and 16 (8.6%) reported the symptom was unchanged or worse 1 year after onset. The risk of persistence was higher for patients reporting a baseline SNOT-22 score ≥ 4 (OR = 3.32; 95% CI 1.32–8.36) as well as for those requiring ≥ 22 days for a negative swab (OR = 2.18; 95% CI 1.12–4.27). Conclusion: A substantial proportion of patients with previous mild-to-moderate symptomatic COVID-19 characterized by new onset of chemosensory dysfunction still complained on altered sense of smell or taste 1 year after the onset.

Background: Using an age and gender matched-pair case-control study, we aimed to estimate the long-term prevalence of psychophysical olfactory, gustatory , and chemesthesis impairment at least one year after SARS-CoV-2 infection considering the background of chemosensory dysfunction in non-COVID-19 population. Methodology: This case-controlled study included 100 patients who were home-isolated for mildly symptomatic COVID-19 between March and April 2020. One control regularly tested for SARS-CoV-2 infection and always tested negative was matched to each case according to gender and age. Chemosensory function was investigated by a comprehensive psychophysical evaluation including ortho- and retronasal olfaction and an extensive assessment of gustatory function. Differences in chemosensory parameters were evaluated through either Fisher’s exact test or Kruskal-Wallis test. Results: The psychophysical assessment of chemosensory function took place after a median of 401 days from the first SARS-CoV-2 positive swab. The evaluation of orthonasal smell identified 46% and 10% of cases and controls, respectively, having olfactory dysfunction, with 7% of COVID-19 cases being functionally anosmic. Testing of gustatory function revealed a 27% of cases versus 10% of controls showing a gustatory impairment. Nasal trigeminal sensitivity was significantly lower in cases compared to controls. Persistent chemosensory impairment was associated with emotional distress and depression. Conclusion: More than one year after the onset of COVID-19, cases exhibited an excess of olfactory, gustatory , and chemesthesis disturbances compared to matched-pair controls with these symptoms being associated to emotional distress and depression.