SARS-CoV-2: low virus load on surfaces in public areas

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has led people to implement preventive measures, including surface and hand disinfection with a disinfectant to avoid viral transmission. The detection of coronaviruses on surfaces implies not always a high danger of infection. Different coronaviruses and SARS-CoV-2 can be detected under experimental conditions on surfaces for many days. However, there are no studies concerning the virus load and the risk for an infection. The aim of our study was to find out if we could detect SARS-CoV-2 with a virus load greater than 10⁶ copies/mL in public areas under real-life conditions. A total of 1200 swabs were performed on different environmental surfaces in public areas: handholds, press buttons in buses, tramways, tubes, elevators, shops, doorknobs in public buildings, public restrooms, touchscreens in shops and public transportation services, supermarket trolleys, banknotes and coins and immediately tested. We used Rapid Covid-19 Antigen Test (Clinitest®) by Siemens Healthineers (Healgen Scientific Limited Liability Company, Houston, USA, respectively, Shanghai International Holding Corp. GmbH (Europe), Hamburg, Germany). During our study, we were not able to detect SARS-CoV-2 with a virus load greater than 10⁶ copies/ml although we pooled the swabs. According to the negative antigen tests and with a theoretically probability calculation of 1/24.000, there seems no relevant risk of infection with SARS-CoV-2 in public areas. For people with underlying diseases or immunosuppression, the risk of transmission respectively infectivity cannot be excluded with this study.