Decreasing Incidence of Chemosensory Changes by COVID‐19 Variant

Abstract

Anecdotal clinical observation suggests that rates of chemosensory dysfunction associated with COVID-19 infection may be decreasing. To investigate, the National COVID Cohort Collaborative database was queried for all patients with and without smell and taste loss within 2 weeks of COVID-19 diagnosis. Six-week periods of peak variant prevalence were selected by using CoVariants.org for analysis. Of 3,678,214 patients with COVID-19 in the database, 616,318 met inclusion criteria during the time intervals of interest, with 3431 having an associated smell or taste disturbance diagnosis. With the initial/untyped variant set as the baseline, the odds ratios for alpha, delta, and omicron (December 27, 2021–February 7, 2022) were 0.50 (95% CI, 0.45-0.55; P < .0001), 0.44 (95% CI, 0.41-0.48; P < .0001), and 0.17 (95% CI, 0.15-0.18; P < .0001), respectively. These data strongly support the clinical observation that patients infected with more recent variants are at a significantly lower risk of developing associated chemosensory loss.

Recovery from Covid-19 smell loss: Two-years of follow up

“…Analysis of demographic variables showed that subjects with age <40 years old had a significantly higher rate of complete recovery and a significantly lower rate of reporting “no recovery at all” than those with age >40 years old. This is in keeping with Petrocelli et al's finding that patient age under 50 is associated with a higher rate of recovery, and our groups prior study showing that age <40 is positively associated with smell recovery [8] , [17] . This finding is likely explained by older individuals having less ability to withstand the olfactory insult associated with COVID-19 infection.…”

“…As such, women in our sample may be more aware of residual smell abnormalities and more likely to place themselves in the partial recovery group than males. Mean age of the men and women who selected “complete recovery” was analyzed to ensure that age was not causing this effect, and no significant difference was found (men: 40.9 ± 14.9 vs women: 41.3 ± 13.0) There was no difference in rates of reporting “no recovery at all” between men and women, a finding corroborated by both our prior study and Saussez et al's 2021 study [17] , [19] .…”

“…This would suggest that the 2 year group is likely an accurate representation of long term covid recovery percentages – and that across the population, closer to 7.5 % of people fail to recover, rather than the 10.3 % seen in the entire cohort. Interestingly, although recent evidence suggests olfactory dysfunction may be less prevalent as variants evolve, it would appear that recovery rates are not similarly improved over time [17] .…”

Distinct smell and taste disorder phenotype of post-acute COVID-19 sequelae

“…Finally, we were not able to investigate effects of immunization, improved medication and the most recent SARS-CoV-2 variants in our study cohorts which were recruited predominantly the wild type and alpha variant outbreaks. In particular, OD following an omicronvariant SARS-CoV-2 infection is reportedly less frequent as compared with the wild type, alpha or delta pathogen (12,13). Hence, there is a continuous need for phenotyping of COVID-19-related OD as new variants of concern emerge.…”

“…Olfactory dysfunction (OD) is a frequent symptom of acute COVID-19 (11), in particular for the wild type, alpha and delta variants of the SARS-CoV-2 virus (12,13). Such COVID-19-related OD may result from injury of upper respiratory epithelial cells or neurons of the olfactory mucosa, olfactory bulb, primary olfactory cortex or secondary projection areas (14,15).…”