Evolution of COVID-19 symptoms during the first 9 months after illness onset

Wynberg, E.; van Willigen, H.; Dijkstra, M.; Boyd, A.; Kootstra, N. A.; van den Aardweg, J. G.; van Gils, M. J.; Matser, A.; de Wit, M. R.; Leenstra, T.; de Bree, G. J.; de Jong, M. D.; Prins, M.

Background: Few longitudinal data on COVID-19 symptoms across the full spectrum of disease severity are available. We evaluated symptom onset, severity and recovery up to nine months after illness onset. Methods: The RECoVERED Study is a prospective cohort study based in Amsterdam, the Netherlands. Participants aged>18 years were recruited following SARS-CoV-2 diagnosis via the local Public Health Service and from hospitals. Standardised symptom questionnaires were completed at recruitment, at one week and month after recruitment, and monthly thereafter. Clinical severity was defined according to WHO criteria. Kaplan-Meier methods were used to compare time from illness onset to symptom recovery, by clinical severity. We examined determinants of time to recovery using multivariable Cox proportional hazards models. Results: Between 11 May 2020 and 31 January 2021, 301 COVID-19 patients (167[55%] male) were recruited, of whom 99/301(32.9%) had mild, 140/301(46.5%) moderate, 30/301(10.0%) severe and 32/301(10.6%) critical disease. The proportion of participants reporting at least one persistent symptom at 12 weeks after illness onset was greater in those with severe/critical disease (81.7%[95%CI=68.7-89.7%]) compared to those with mild or moderate disease (33.0%[95%CI=23.0-43.3%] and 63.8%[95%CI=54.8-71.5%]). At nine months after illness onset, almost half of all participants (42.1%[95%CI=35.6-48.5]) continued to report [≥]1 symptom. Recovery was slower in participants with BMI[≥]30kg/m2 (HR 0.51[95%CI=0.30-0.87]) compared to those with BMI<25kg/m2, after adjusting for age, sex and number of comorbidities. Conclusions: COVID-19 symptoms persisted for nine months after illness onset, even in those with mild disease. Obesity was the most important determinant of time to recovery from symptoms.