Do we cause false positives? An experimental series on droplet or airborne SARS-CoV-2 contamination of sampling tubes during swab collection in a test center.

The rapid spread of the coronavirus disease 2019 pandemic urged immense testing capacities as one cornerstone of infection control. Many institutions opened outpatient SARS-CoV-2 test centers to allow large number of tests in comparatively short time frames. With increasing positive test rates, concerns for a possible airborne or droplet contamination of specimens leading to false-positive results were raised. In our experimental series performed in a dedicated SARS-CoV-2 test center, 40 open collection tubes placed for defined time periods in proximity to individuals were found to be SARS-CoV-2 negative. These findings argue against false-positive SARS-CoV-2 results due to droplet or airborne contamination.

Universal Admission Screening for SARS-CoV-2 Infections among Hospitalized Patients, Switzerland, 2020.

Switzerland began a national lockdown on March 16, 2020, in response to the rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We assessed the prevalence of SARS-CoV-2 infection among patients admitted to 4 hospitals in the canton of Zurich, Switzerland, in April 2020. These 4 acute care hospitals screened 2,807 patients, including 2,278 (81.2%) who did not have symptoms of coronavirus disease (COVID-19). Overall, 529 (18.8%) persons had >1 symptom of COVID-19, of whom 60 (11.3%) tested positive for SARS-CoV-2. Eight asymptomatic persons (0.4%) also tested positive for SARS-CoV-2. Our findings indicate that screening on the basis of COVID-19 symptoms, regardless of clinical suspicion, can identify most SARS-CoV-2-positive persons in a low-prevalence setting.

Does respiratory co-infection facilitate dispersal of SARS-CoV-2? investigation of a super-spreading event in an open-space office.

BACKGROUND: Super-spreaders are individuals infecting disproportionately large numbers of contacts. They probably play a crucial role in the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We describe a super-spreading event within a team working in an open-space office and investigate factors potentially having facilitated SARS-CoV-2 transmission. METHODS: In this retrospective cohort study, semi-structured telephone interviews with all team members were carried out to identify symptoms, contacts, and adherence to basic hygiene measures. During site visits, we gathered information about workplace and seating arrangements. The secondary attack rate in office and households was calculated. Potential respiratory viral co-infections were assessed by multiplex PCR. SARS-CoV-2 whole-genome sequencing was performed using a tiled-amplicon sequencing approach. RESULTS: Of 13 team members, 11 fell ill with Coronavirus disease 2019 (COVID-19). Due to the sequence of events and full genome sequence data, one person was considered the index case for this outbreak, directly infecting 67 to 83% of the teammates. All team members reported repetitive close contacts among themselves during joint computer work, team meetings and a "Happy Birthday" serenade. Two individuals shared nuts and dates. The arrangement of the office and meeting rooms precluded sufficient adherence to physical distancing. The index case and a further individual were diagnosed with an adenovirus serotype 4 co-infection. CONCLUSION: We identified several environmental and behavioral factors that probably have facilitated the transmission of SARS-CoV-2. The relevance of the adenovirus co-infection remains unclear and merits further investigation.