Evaluation of non-invasive oral sampling versus nasopharyngeal swab for RTq-PCR detection of SARS-CoV-2 RNA

The global spread of SARS-CoV-2 has resulted in a public health crisis and major economic impact, with millions of confirmed cases and deaths worldwide. An important aspect of controlling the spread of the virus is testing individuals for COVID-19. Currently, the gold standard is the association of RT-qPCR with the Nasopharyngeal Swab (Ns), which is uncomfortable and requires specialized personnel for sample collection. Mass testing, unprecedented in human history, leads to the search for innovations and facilities in the methodology, but which maintains diagnostic security, even in the face of new variants of the virus. This study aimed to evaluate a less invasive alternative method, collecting samples from the oral mucosa with a swab (Os). For comparison, the same patients were tested using biological material collected through Os and Ns. Samples were processed and analyzed by RTq-PCR. Results showed 100% concordance between Ns and Os samples from elderly patients, and SARS-CoV-2 was detected in saliva samples up to 14 days after the onset of symptoms in 31.25% of hospitalized patients. Our data and conclusion provide an important base for future studies of standardization and validation of the procedure described here. Using a more comfortable method could increase population adherence to testing and contribute to controlling the transmission of COVID-19.