Background: Coronavirus disease 2019 (COVID-19) has spread, causing a worldwide pandemic, and prolonged effects are emerging (1, 2). The term “long COVID” describes illness in persons who continue to report lasting effects after infection (3, 4). To date, little information exists about outpatient settings in this novel disease where 81% of cases are reportedly on the mild end of the spectrum (5). Informing patients and physicians about COVID-19 symptom evolution may help them recognize the time course of the disease, legitimize patients' concerns, and reassure them when possible. Messages around potentially persisting symptoms could also assist in reinforcing public health measures to avoid the spread of infection.

Objective: To describe COVID-19 symptom evolution and persistence in an outpatient setting in Geneva, Switzerland, from day 1 through day 30 to 45 after diagnosis.

Methods: From 18 March to 15 May 2020, the Geneva University Hospitals (sole and largest public hospital in Geneva) was 1 of 5 available testing centers and served more than 50% of patients with COVID-19 in the Geneva canton. Only symptomatic persons were tested during that period. Because many practices were closed, persons who were not hospitalized at baseline could benefit from remote follow-up with an ambulatory care center (a process called COVICARE) in case their primary care physician was unavailable for follow-up care (a full description is available at www.covicare24.com). Exclusion criteria were refusal to provide consent and administrative reasons (living outside the Geneva canton).

Most patients were called every 48 hours for the first 10 days with a standardized interview inquiring about self-reported symptoms (Supplement). Follow-up during the 10 days was suspended if patients declined follow-up, clinically recovered, or were hospitalized (Figure 1). Participants were called every 24 hours if they reported deteriorating clinical symptoms; those who were unreachable (eligible minus reached) were called again the next day. All patients were then contacted again 30 to 45 days after diagnosis. To address the varying frequency of contacts during the first 10 days, we combined assessments into 2-day intervals: days 1 to 2 through days 9 to 10. When 2 measurements were available, we included only the first observation per assessment interval.