Prevalence, symptoms, and associated factors of long COVID: a retrospective cohort study based on data from two major German health authorities

BACKGROUND: Acute SARS-CoV-2 infection has caused substantial morbidity and mortality worldwide. As the pandemic subsided, persistent symptoms gained increasing attention. Time-based definitions distinguish ongoing symptomatic COVID-19 (weeks 4–12) from post-COVID syndrome ( > 12 weeks). Consistent with these time-based definitions, long COVID is commonly used as an umbrella term for symptoms persisting for ≥4 weeks post-infection (including ongoing symptomatic COVID-19 and post-COVID-19 syndrome). Reported prevalence estimates vary widely, with meta-analyses suggesting 43–80% for persistent symptoms, mainly based on data from hospitalised patients. However, evidence on long COVID among nonhospitalised adults in Germany remains limited. The aim of this study was to estimate the prevalence, symptoms, and associated factors of long COVID among quarantined adults in two German regions, including the early post-acute phase (4–12 weeks), a key predictor of post-COVID syndrome. METHODS: We conducted a retrospective cohort study based on an online questionnaire to estimate the prevalence, symptoms, and associated factors of long COVID. We included 6846 adults with a laboratory-confirmed SARS-CoV-2 infection in 2021 who were reported to the health authorities in Cologne and Augsburg (Germany) and subsequently enrolled in the CoCo-Fakt online monitoring study. RESULTS: The prevalence of long COVID was 14.6% (n = 997), with women being significantly more affected than men (16.4% vs 11.8%, p < 0.001). The most reported symptoms were fatigue (76.8%, n = 763), concentration and cognitive impairment (60.1%, n = 597), and dyspnoea (48.9%, n = 486). Chronic diseases (odds ratio [OR] = 1.563; p < 0.001; 95% CI: 1.2–2.0) and the severity of acute symptoms (OR = 141.809 in severe cases; p < 0.001; 95% CI: 19.8–1016.7) were identified as factors significantly influencing the occurrence of long-term symptoms (Nagelkerke R2 = 0.19). CONCLUSION: Individuals, especially women, with pre-existing chronic conditions or severe acute SARS-CoV-2 infection were particularly affected. Targeted screening of high-risk groups can facilitate early detection and personalised care, helping identify the need for early intervention to prevent the development of post-COVID syndrome. CLINICAL TRIAL NUMBER: Not applicable.