COVID-19 screening in a healthcare or community setting: complexity of saliva as a specimen for PCR-based testing

Testing for SARS-CoV-2 has highly significant clinical and epidemiological implications in the current COVID-19 pandemic. Reverse transcription PCR (RT-PCR)-based assays are the predicate method for detecting the virus, primarily from nasopharyngeal swab (NPS) samples. However, collection of NPS samples poses certain challenges that include exposure risk to healthcare workers, supply chain constraints pertaining to swabs and personal protective equipment and self-collection being difficult and less sensitive. Furthermore, several reports have highlighted the relatively poor sensitivity of NPS samples in early infection and longitudinal testing [1–3]. Amid these challenges, several other sample types are under investigation for COVID-19 testing, of which saliva samples are of significant interest owing to their ease of collection and alleviation of some of the challenges with NPS sampling. In the US, the FDA has approved saliva-based collection methods for laboratories submitting for emergency use authorization