Saliva vs. swabs for SARS-CoV-2 detection

Saliva can be a reliable and sensitive sample type for SARS-CoV-2 detection when appropriate sample processing methods are applied. Studies describing the detection of SARS-CoV-2 in saliva samples have greatly varying methods with large discrepancies between results. When introducing new methods, labs should replicate methods that are high in sensitivity and best suited to their available resources. We reviewed 58 studies conducted in 2020, evaluating saliva as a sample type and found that the majority found saliva to be at least equal to, and if not better, as nasopharyngeal swabs for SARS-CoV-2 detection.

In our recent publication, Saliva as a gold-standard sample type for SARS-CoV-2 detection, in which we reviewed saliva and swab-based approaches, we found that saliva can be a reliable and sensitive sample type for SARS-CoV-2 detection when appropriate sample processing methods are applied. Studies showing greater/similar saliva sensitivities than their reference tests are highlighted green (n=40), lower saliva sensitivities are highlighted red (n=14), and mixed finding studies are highlighted yellow (n=4). As these studies (n=44) indicated that a notable proportion of COVID-19 cases (up to 47.5%, median = 10%) were undetected by swabs but detected by saliva alone, nasopharyngeal swab testing alone may not be a reliable reference standard.