Epidemiological and clinical characteristics of SARS-CoV-2 infections at a testing site in Berlin, Germany, March and April 2020 – A cross-sectional study

Maechler, Friederike; Gertler, Maximilian; Hermes, Julia; van Loon, Welmoed; Schwab, Frank; Piening, Brar; Rojansky, Shay; Hommes, Franziska; Kausch, Franka; Lindner, Andreas K.; Burock, Susen; Rössig, Heike; Hartmann, Claudia; Kirchberger, Valerie; Thieme, Alexander; Behnke, Michael; Gastmeier, Petra; Mockenhaupt, Frank P.; Seybold, Joachim

OBJECTIVE: In Berlin, the first public SARS-CoV-2 testing site started one day after the first case in the city occured. We describe epidemiological and clinical characteristics and aim at identifying risk factors for SARS-CoV-2 detection during the first six weeks of operation. METHODS: Testing followed national recommendations, but was also based on the physician´s discretion. We related patient characteristics to SARS-CoV-2 test positivity for exploratory analyses using a cross-sectional, observational study design. RESULTS: Between March 3 and April 13, 2020, 5179 patients attended the site (median age 34 years; IQR 26-47 years). The median time since disease onset was 4 days (IQR 2-7 days). Among 4333 patients tested, 333 (7.7%) were positive. Test positivity increased up to 10.3% (96/929) during the first three weeks and then declined, paralleling Germany’s lock-down and the course of the epidemic in Berlin. Strict adherence to testing guidelines resulted in 10.4% (262/2530) test positivity, compared to 3.9% (71/1803) among patients tested for other indications. A nightclub was a transmission hotspot; 27.7% (26/94) of one night’s visitors were found positive. Smell and/or taste dysfunction indicated COVID-19 with 85.6% specificity (95%CI 82.1-88.1%). Some 4% (14/333) of those infected were asymptomatic. Risk factors for detection of SARS-CoV-2 infection were recent contact to a positive case (second week after contact, OR 3.42; 95%CI 2.48-4.71), travel to regions of high pandemic activity (e.g. Austria, OR 4.16; 95%CI 2.48-6.99), recent onset of symptoms (second week, OR 3.61; 95%CI 1.87-6.98), and an impaired sense of smell/taste (4.08; 95%CI 2.36-7.03). CONCLUSIONS: In this young population, early-onset presentation of COVID-19 resembled flu-like symptoms, except for smell and/or taste dysfunction. Risk factors for SARS-CoV-2 detection were return from regions with high incidence and contact to confirmed SARS-CoV-2 cases, particularly when tests were administered within the first two weeks after contact and/or onset of symptoms.