Duration and severity of chemosensory dysfunction following COVID-19 infection

A significant number of healthcare workers experience persistent chemosensory dysfunction months after COVID-19 infection. Duration, severity, and trajectory of these post-infectious symptoms were examined in a cohort of 726 Quebec healthcare workers.

Chemosensory dysfunction is a key symptom of COVID-19 infection and it is demonstrated that 60 % of COVID-19 patients experiences alterations in smell or taste. Persistent post-infectious chemosensory dysfunction is reported in 20% of the patients [1]. This study, presented by Nicholas Bussière (University of Quebec, Canada), investigated chemosensory dysfunction following COVID-19 infection by analysing duration, severity, and trajectory of these symptoms [2].

Healthcare workers who were registered in the Quebec National Institute of Public Health with a positive SARS-CoV-2 diagnosis were invited to enter the study 4 months after diagnosis. An online questionnaire was used to evaluate chemosensory dysfunction (olfactory, gustatory, trigeminal) pre-infection (retrospectively), during the acute phase (retrospectively), and at time of questionnaire completion; results being reported on a scale from 0 to 10 (0: no perception; 10: very strong perception). Next to that, a previously validated chemosensory dysfunction home test (CDHT) was used to objectify the symptoms. This test was based around products found in North American households (jam, peanut butter, coffee, salt) and contained an olfactory and gustatory part.

There were 726 healthcare workers (mean age 41.9; 84% female) who completed the questionnaire, on average 150.1 days after diagnosis. Self-reported olfaction (pre-infection: 8.98/10; acute phase: 2.85/10) and gustation (pre-infection: 9.20/10; acute phase: 3.59/10) dropped strongly during the acute phase of the disease. These scores improved at time of questionnaire completion for both smell (7.41/10) and taste (8.05/10). Nonetheless, 50.4% (smell) and 40.5% (taste) of the participants still reported alterations at time of questionnaire completion. This was 79.1% and 79.5%, respectively, during the acute phase of the infection. The CDHT showed that objective dysfunction was present in 18.9% of the participants. Bussière mentioned that the possibility of recall bias and variability in CDHT (product quality, expiration date, brand) are limitations of this study.

In conclusion, persistent CD occurred in approximately 1 out of 5 COVID-19 patients in this study. Reported chemosensory alterations differed between subjective and objective data collection.

1. Hajikhani B, et al. Physiol Rep. 2020 Sep;8(18):e14578.
2. Bussière N, et al. Persistent Chemosensory Dysfunction Associated with COVID-19 Infection in a Cohort of Over 700 Health Care Workers. S21.005, AAN 2021 Virtual Congress, 17-22 April.

Posted on 22 April, 202117 June, 2021