Chemosensory dysfunctions induced by COVID-19 can persist up to 7 months: A study of over 700 healthcare workers

Abstract

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.

High prevalence of olfactory disorders 18 months after contracting COVID-19: a case-control study

“…Upon infection, these cells degenerate which disturbs the local environment which, crucially, results in cell death of olfactory receptor neurons and associated olfactory dysfunction (Cooper et al, 2020; Xydakis et al, 2021). The olfactory system demonstrates, however, a very good ability to regenerate (Reden et al, 2006) which might explain why most of SARS-CoV-2 infected individuals regain olfactory abilities within weeks following the acute phase (Bussiere et al, 2021; Bussiere et al, 2022). It is not yet clear why some individuals do not completely regain their olfactory abilities.…”

“…However, a non-negligeable proportion of patients exhibits chronic olfactory dysfunction after COVID-19 (McWilliams et al, 2022). Estimations of the prevalence of olfactory dysfunction more than 6 months after an infection by SARS-CoV-2 – a threshold for chronicity of olfactory dysfunction – vary widely (Boscolo-Rizzo et al, 2022; Bussiere et al, 2021; Bussiere et al, 2022; Capelli & Gatti, 2021; Hopkins et al, 2021; Lechien et al, 2021; Ohla et al, 2022). Critically, a recent assessment of olfactory dysfunction based on subjective reports only, suggests that two years after contracting COVID-19, a staggering 61% still experience olfactory dysfunction (McWilliams et al, 2022).…”

New Onset of Smell and Taste Loss Are Common Findings Also in Patients With Symptomatic COVID‐19 After Complete Vaccination

“…In the future, it will be necessary to establish what the recovery rate is in these patients. Residual CD are in fact turning out to be one of the most frequent symptoms of long‐COVID‐19, with persistent anosmia rates beyond 6 months varying between 1% and 11% 10–15 . If this prevalence were so high even in vaccinated subjects, we could still have a high number of subjects who will require assistance for such disabling disorders.…”

Impairments in odour detection and hedonic ratings of unpleasant smells in asymptomatic university students as SARS‐Cov‐2 emerged locally

“…A recent meta-analysis found increased risk of self-reported/medical chart documented smell loss in those with less severe illness compared to those who were hospitalized with severe COVID-19 symptoms (Purja et al, 2021). Similarly, chemosensory impairemnt is a widely reported by patients who develop 'post-COVID syndrome' or 'long COVID' and continue to experience protracted symptoms following recovery of acute COVID-19, who disproportionaly experience mildto-moderate acute illness severity (Boscolo-Rizzo et al, 2021;Bussière et al, 2021;Walsh-Messinger et al, 2021).…”