Gargle and mouthwash can replace nasopharyngeal swab sampling with a concentration method for diagnosis of COVID-19

Diagnosis of COVID19 is based on RT-PCR testing of nasopharyngeal swab samples. There is limited data about the performance of saliva and mouthwash samples by RT-PCR. We developed a new method for concentrating gargle and mouthwash samples to be used in RT-PCR. In our study, we aimed to investigate the performance of concentration of gargle and mouthwash samples in detection of SARS-CoV-2. Samples were collected from patients in 11 centers. Gargle and mouthwash samples were concentrated using MyMagiCon-RW100®. Nasopharyngeal swab, gargle and mouthwash and concentrated gargle and mouthwash samples were tested by RT-PCR for the presence of SARS-CoV2 and the results were compared. The viral RNA was detected in 47.5% of nasopharyngeal swab samples, in 28.8% of gargle and mouthwash before concentration and in 37.5% gargle and mouthwash samples after concentration. By concentration the number of SARS-CoV2 RNA positive samples increased 16.6%. Concentrated gargle and mouthwash sampling can be an alternative method to nasopharyngeal swab sampling in rapid and accurate diagnosis of COVID-19.