COVID-19 Has Long Term Effects on Chemosensory Functions

Importance: A number of studies have revealed either self-reported chemosensory alterations in large groups or objective quantified chemosensory impairments in smaller populations of patients diagnosed with COVID-19. However, due to the great variability in published results regarding COVID-19-induced chemosensory impairments and their follow-up, prognosis for chemosensory functions in patients with such complaints remains unclear. Objective: To describe the various chemosensory alterations associated with COVID-19 and their prevalence and evolution at 3 to 7 months after infection. Design, Setting, and Participants: A follow-up study of 704 health care workers with a RT-PCR confirmed SARS-CoV-2 infection between 28/2/2020 and 14/6/2020 was conducted 3 to 7 months after onset of symptoms. Data were collected with an online questionnaire. Participant had to be [≥]18 years old without respiratory illness in the 2 weeks prior to questionnaire completion. Main outcomes and measures: Outcomes included differences in reported chemosensory self-assessment of olfactory, gustatory, and trigeminal functions across time points and Chemosensory Perception Test scores from an easy-to-use at-home self-administered chemosensory test. Results: Among the 704 health care worker participants, 593 (84.2%) were women, the mean (SD) age was 42 (12) years and the questionnaire was answered on average 4.8 (0.8) months after COVID-19. During COVID-19, a decrease in olfactory, gustatory, and trigeminal sensitivities were reported by 81.3%, 81.5% and 48.0% respectively. Three to seven months later, reduced sensitivity was still reported by 52.0%, 41.9% and 23.3% respectively. Chemosensory Perception Test scores indicate that 19.5% of participants had objective olfactory impairment. Conclusions and relevance: A significant proportion of COVID-19 cases have persistent chemosensory impairments at 3 to 7 months after their infection but the majority of those who had completely lost their olfactory, gustatory and trigeminal sensitivity have improved. Given the possible neurological underpinnings of this observation and the important number of individuals infected with SARS-CoV-2, further longitudinal studies are needed to better characterize this phenotype and to report eventual post-COVID-19 neurological sequelae.