J Infect . Clinical performance and accuracy of a qPCR-based SARS-CoV-2 mass-screening workflow for healthcare-worker surveillance using pooled self-sampled gargling solutions: a cross-sectional study

[tetano]

J Infect


. 2021 Sep 6;S0163-4453(21)00451-5.
doi: 10.1016/j.jinf.2021.08.047. Online ahead of print.
Clinical performance and accuracy of a qPCR-based SARS-CoV-2 mass-screening workflow for healthcare-worker surveillance using pooled self-sampled gargling solutions: a cross-sectional study


Flaminia Olearo ¹ , Dominik Nörz ¹ , Armin Hoffman ¹ , Moritz Grunwald ¹ , Kimani Gatzemeyer ¹ , Martin Christner ¹ , Anna Both ¹ , Cristina Elena Belmar Campos ¹ , Platon Braun ² , Gabriele Andersen ² , Susanne Pfefferle ³ , Antonia Zapf ⁴ , Martin Aepfelbacher ¹ , Johannes K M Knobloch ¹ , Marc Lütgehetmann ⁵



Affiliations

• PMID: 34499947
• DOI: 10.1016/j.jinf.2021.08.047

Abstract

Introduction: The large number of asymptomatic SARS-CoV-2 infections necessitates general screening of employees. We evaluate the performance of a SARS-CoV-2 screening program in asymptomatic healthcare-workers (HCW), utilizing self-sampled gargling-solution and sample pooling for RT-qPCR.
Methods: We conducted a cross-sectional retrospective study to collect real-life data on the performance of a screening-workflow based on automated-pooling and high-throughput qPCR testing over a 3-month-period at the University Hospital Hamburg.
Results: Matrix validation reveals that lower limit of detection for SARS-CoV-2 RNA in gargling-solution was 180 copies/mL (5-sample-pool). A total of 55,122 self-collected gargle samples (=7,513 HCWs) was analyzed. The median time to result was 8.5 hours (IQR 7.2-10.8). Of 11,192 pools analyzed, 11,041 (98.7%) were negative, 69 (0.6%) were positive and 82 (0.7%) were invalid. Individual testing of pool participants revealed 57 SARS-CoV-2 previously unrecognized infections. All 57 HCWs were either pre-symptomatic or asymptomatic (prevalence 0.76%,CI95%0.58-0.98%). Accuracy based on HCWs with gargle-solution and NP-swab available within 3-day-interval (N=521) was 99.5% (CI95%98.3-99.9%), sensitivity 88.9% (CI95%65.3-98.6%) while specificity 99.8% (CI95%98.9-99.9).
Conclusion: This workflow was highly effective in identifying SARS-CoV-2 positive HCWs, thereby lowering the potential of inter-HCW and HCW-patient transmissions. Automated-sample-pooling helped to conserve qPCR reagents and represents a promising alternative strategy to antigen testing in mass-screening programs.

Keywords: SARS Coronavirus 2 RT-PCR Testing; mass Screening; pooling gargle solution.