Saliva as a promising biofluid for SARS-CoV-2 detection during the early stages of infection.

Background: Diagnostic testing for coronavirus disease (COVID)-19 is performed using nasopharyngeal swabs. This type of sampling is uncomfortable for the patient, dangerous for health workers, and its high demand has led to a global shortage of swabs. One of the alternative specimens is saliva. However, the optimal conditions for the test have not been established.

Methods: Reverse transcription-polymerase chain reaction was used to detect the viral genome in saliva samples kept at room temperature, in the fridge or frozen for 2 days. In addition, the influence of brushing teeth and feeding on the detection of the virus in saliva was addressed. Finally, the efficiency of saliva in revealing the presence of the virus during the hospitalization period was determined in children.

Results: The viral genome was consistently detected regardless of the storage conditions of saliva samples. Brushing teeth and feeding did not influence the sensitivity of the test. In hospitalized children, positive results were obtained only during the early days.

Conclusions: These results support the idea of the use of saliva as an alternative specimen for diagnostic testing for COVID-19. The viral genome is stable and endures perturbations in the oral cavity. However, clearance of the virus from the mouth during the infection may limit the use of the test only to the early stages of the disease.