Overcoming limitations in the availability of swabs systems used for SARS-CoV-2 laboratory diagnostics

Nairz, Manfred; Bellmann-Weiler, Rosa; Ladstätter, Miriam; Schüllner, Falko; Zimmermann, Martina; Koller, Anna-Maria; Blunder, Silvia; Naschberger, Helene; Klotz, Werner; Herold, Manfred; Kerndler, Sylvia; Jeske, Martina; Haschka, David; Petzer, Verena; Schroll, Andrea; Sonnweber, Thomas; Tancevski, Ivan; Fritsche, Gernot; de Araujo, Mariana E. G.; Stasyk, Taras; Huber, Lukas A.; Griesmacher, Andrea; Theurl, Igor; Weiss, Günter

The diagnosis of COVID-19 relies on the direct detection of SARS-CoV-2 RNA in respiratory specimens by RT-PCR. The pandemic spread of the disease caused an imbalance between demand and supply of materials and reagents needed for diagnostic purposes including swab sets. In a comparative effectiveness study, we conducted serial follow-up swabs in hospitalized laboratory-confirmed COVID-19 patients. We assessed the diagnostic performance of an in-house system developed according to recommendations by the US CDC. In a total of 96 serial swabs, we found significant differences in the accuracy of the different swab systems to generate a positive result in SARS-CoV-2 RT-PCR, ranging from around 50 to 80%. Of note, an in-house swab system was superior to most commercially available sets as reflected by significantly lower Ct values of viral genes. Thus, a simple combination of broadly available materials may enable diagnostic laboratories to bypass global limitations in the supply of swab sets.