Post-infection symptoms up to 24 months after COVID-19: a matched cohort study in Berlin, Germany

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Abstract Background Long-term health consequences after mild COVID-19 are not well described. Our aim was to estimate their prevalence and describe the time course of signs and symptoms for a period of up to 24 months after confirmed SARS-CoV-2 infection. Methods We conducted a cohort study matched for age, sex, and test week among individuals who had attended the public COVID-19 test center at Charité - Universitätsmedizin Berlin, Germany. In early 2022, 576 former COVID-19 patients (>95% non-hospitalised) and 302 uninfected individuals responded to a questionnaire on retrospective monthly symptoms since the test date up to 24 months after. Results Symptoms compatible with long COVID were present in 42.9% (247/576) of former COVID-19 patients, compared with 21.2% (64/302) in the uninfected group. In former patients, unadjusted odds ratios (OR) were highest for disturbed taste/smell (OR 9.1 [95% CI: 4.0 - 21.1]), memory difficulties (OR 5.1 [95% CI: 2.9 - 8.9]) and shortness of breath at rest (OR 4.5 [95% CI: 1.9 - 10.6]). Whilst in most former COVID-19 patients, symptoms occurred in one coherent period and resolved after a median of 6.5 months, taste/smell disturbance and neurological/cognitive symptoms showed longer times until recovery and 28.7% (31/108) still reported long COVID-compatible symptoms 18 months after initial COVID-19. Factors associated with long COVID-compatible symptoms included hospitalisation (OR 4.2 [95% CI: 1.7 - 10.8], symptomatic COVID-19 infection (OR 3.4 [95% CI: 1.9 - 6.3], low household income (OR 1.8 [95% CI: 1.2 - 2.7], and female sex (OR 1.7 [95% CI: 1.2 - 2.4]). Conclusions Post-infection symptoms in mild COVID-19 mostly persist for about half a year, but sometimes longer. Among uninfected individuals who never experienced COVID-19, 21.2% also reported long COVID-compatible symptoms. The current long COVID definition might require revision to prevent misclassification and over-reporting, and to improve diagnosis and prevalence estimates. Key messages • A more precise definition of long COVID is needed to prevent over-reporting of symptoms compatible with long COVID, and to improve diagnosis, prevalence estimates and research harmonisation. • Post-infection symptoms after mild COVID-19 are common, mostly persist for about half a year but sometimes longer for more than 20 months.