Efficacy of SARS-CoV-2 detection from used surgical masks compared with standard detection method

The real-time reverse transcription-polymerase chain reaction (RT-PCR) test is the gold standard for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection. Proper specimen collection and obtaining a sufficient specimen are the most essential steps for laboratory diagnosis. The nasopharyngeal (NP) swab is recommended as the reference collection method. However, NP swab collection is invasive and uncomfortable for patients and poses some risk to healthcare workers. This study aimed to compare the efficacy of SARS-CoV-2 RNA detection from surgical masks with the NP swab method using RT-PCR testing. Of 269 patients, RT-PCR RNA from NP swabs was detected among 82 patients (30.5%) and was undetected among 187 patients (69.5%). All patients were tested for SARS-CoV-2 RNA from surgical masks. SARS-CoV-2 RNA was detected in 25/82 (30.5%) surgical mask filters, while undetected among 57 (69.5%). For the surgical mask with an average use time of 7.05 h, the sensitivity was 30.5%, the specificity was 100.0%, with positive predictive value of 100.0% and negative predictive value of 76.2%. Therefore, surgical masks could be an alternative non-invasive specimen source for SARS-CoV-2 RT-PCR testing. The results of our study suggest that the test could be employed after wearing surgical masks for at least 8-12 h, with increased sensitivity when used for more than 12 h.