A description and analysis of covid-19 in a populationrepresentative cohort

Background: Most data on COVID-19 was collected in hospitalized cases. Much less is known about the spectrum of disease in entire populations including nonhospitalized patients and minors. In this study, we examine a representative cohort in an administrative district in Southern Germany who tested positive for SARS-CoV-2 between February and June of 2020. Methods: We contacted all confirmed SARS-CoV-2 cases in an administrative district in southern Germany. Consenting participants answered a retrospective survey either via a telephone, electronically or via mail. Clinical and sociodemographic features were compared between hospitalized and non-hospitalized patients. Additionally, we assessed potential risk factors for hospitalization and time to hospitalization in a series of regression models. As predictors we assessed age as a continuous variable, sex, smoking as a continuous variable using pack years, living with children (age <18), hypertension (yes/no), coronary heart disease (CHD;yes/no), diabetes (type 1 or type 2;yes/no) and lung conditions (yes/no). Lung conditions were defined as a combined variable of either COPD, asthma treated with medications, any other lung disease or previously performed lung surgery. Secondly, we estimated the influence of the same covariates on the time from symptom onset to hospitalization with a Cox proportional hazard ratio (HR) model. Results: We included 897 participants in our study, 69% out of 1,305 total cases in the district with a mean age of 47 years (range 2-97), 51% of which were female and 47% had a pre-existing illness. The percentage of asymptomatic, mild (symptomatic, no hospitalization), moderate (leading to hospital admission) and critical illness (requiring mechanical ventilation) was 54 patients (6%), 713 (79%), 97 (11%) and 16 (2%), respectively. Seventeen patients (2%) died. The most prevalent symptoms were fatigue (65%), cough (62%) and dysgeusia (60%). The risk factors for hospitalization included older age (OR 1.05 per year increase;95% CI 1.04-1.07) preexisting lung conditions (OR 3.09;95% CI 1.62-5.88). Female sex was a protective factor (OR 0.51;95% CI 0.33-0.77). Conclusion: This population-representative analysis of COVID-19 cases confirms age, male sex and preexisting lung conditions but not cardiovascular disease as risk factors for severe illness. Almost 80% of infection take a mild course, whereas 13% of patients suffer moderate to severe illness.