Reviewed By: Erica Stohs, MD, MPH, University of Nebraska
In this prospective longitudinal observational study of patients self-reporting their COVID-19 symptoms via study app, differences in symptoms between delta and omicron variants are revealed.
Eligible participants were aged 16–99 years in the UK, received at least two doses of any SARS-CoV-2 vaccine, were symptomatic, and logged a positive test result into an app called ZOE. The primary outcome was the likelihood of developing a given symptom of the 32 monitored in the app or hospital admission within 7 days before or after the positive test. Of the more than 63,000 participants utilizing the app, those occurring during the delta (June 1- Nov. 27, 2021) and omicron (Dec. 20, 2021-Jan. 17, 2022) periods were included. Each group included 4990 participants who were matched 1:1 for age, sex and vaccine dose.
Based on adjusted odds ratios, sore throat and hoarse voice were significantly more likely to be present with omicron infection than delta, whereas loss of smell was least likely. Four symptoms were significantly less prevalent during omicron: loss of smell, altered smell, sneezing and eye soreness. There was a lower rate of hospital admission during omicron compared to delta. Symptom onset and duration were shorter during omicron period, consistent with prior studies.
Menni C, et al. “Symptom prevalence, duration, and risk of hospital admission in individuals infected with SARS-CoV-2 during periods of omicron and delta variant dominance: a prospective observational study from the ZOE COVID study.” Lancet 2022;399:1618-24. DOI: https://doi.org/10.1016/S0140-6736(22)00327-0.