Comparing SARS‐CoV‐2 Viral Load in Human Saliva to Oropharyngeal Swabs, Nasopharyngeal Swabs, and Sputum: A Systematic Review and Meta‐Analysis

A systematic review and meta‐analysis were conducted to investigate the SARS‐CoV‐2 viral load in human saliva and compared it with the loads in oropharyngeal swabs, nasopharyngeal swabs, and sputum. In addition, the salivary viral loads of symptomatic and asymptomatic COVID‐19 patients were compared. Searches were conducted using four electronic databases: PubMed, Embase, Scopus, and Web of Science, for studies published on SARS‐CoV‐2 loads expressed by C T values or copies/mL RNA. Three reviewers evaluated the included studies to confirm eligibility and assessed the risk of bias. A total of 37 studies were included. Mean C T values in saliva ranged from 21.5 to 39.6 and mean copies/mL RNA ranged from 1.91 × 10 1 to 6.98 × 10 11 . Meta‐analysis revealed no significant differences in SARS‐CoV‐2 load in saliva compared to oropharyngeal swabs, nasopharyngeal swabs, and sputum. In addition, no significant differences were observed in the salivary viral load of symptomatic and asymptomatic COVID‐19 patients. We conclude that saliva specimen can be used as an alternative for SARS‐CoV‐2 detection in oropharyngeal swabs, nasopharyngeal swabs, and sputum.