Novel multiple swab method enables high efficiency in SARS‐CoV‐2 screenings without loss of sensitivity for screening of a complete population

Schmidt, Michael; Hoehl, Sebastian; Berger, Annemarie; Zeichhardt, Heinz; Hourfar, Kai; Ciesek, Sandra; Seifried, Erhard

BACKGROUND: In the pandemic, testing for SARS‐CoV‐2 by RT‐PCR is one of the pillars on which countermeasures are based. Factors limiting the output of laboratories interfere with the effectiveness of public health measures. Conserving reagents by pooling samples in low‐probability settings is proposed, but may cause dilution and loss of sensitivity. Blood transfusion services had experience in performance of high throughput NAT analysis and can support the national health system by screening of the inhabitants for SARS‐COV‐2. METHODS: We evaluated a new approach of a multiple swab method by simultaneously incubating multiple respiratory swabs in a single tube. Analytical sensitivity was constant up to a total number of 50 swabs. It was consequently applied in the testing of 50 symptomatic patients (five‐sample pools) as well as 100 asymptomatic residents of a nursing home (ten‐sample pools). RESULTS: The novel method did not cause false negative results with non‐significantly differing Ct values between single swab and multiple swab NAT. In two routine applications, all mini pools containing positive patient samples were correctly identified. CONCLUSIONS: The new method enables countries to increase the total number of testing significantly. The multiple swab method is able to screen system relevant groups of employees frequently. Secondly the example in Germany shows that blood transfusion services can support general health systems with their experience in NAT and their high throughput instruments. Screening of a huge number of inhabitants is currently the only option to prevent a second infection wave and enable exit strategies in many countries. This article is protected by copyright. All rights reserved.