SARS-CoV2 antigen in whole mouth fluid may be a reliable rapid detection tool.

Dear Editor, SARS‐CoV2, transmitted through respiratory secretions within close contacts, primarily infects epithelial/endothelial cells lining the respiratory mucosae. Nasopharyngeal swab (NPS), the favoured sample for reverse transcriptase‐polymerase chain reaction (RT‐PCR) retrieves SARS‐CoV2‐infected cells with minimal aerosol formation (Wang et al. 2020; CDC guidelines, 2020). However, NPS collection is somewhat invasive with discomfort, requires medical/technical expertise, and might not be feasible in remote villages, especially in developing countries like India. On the other hand, epithelial cells of the oral mucosa abundantly carry angiotensin converting enzyme‐2 (ACE‐2) receptors that bind SARS‐CoV2 (Huang et al. 2020; Xu et al. 2020). Whole mouth fluid (WMF) is used for diagnosis in many diseases (Azzi et al. 2020; Malamud & Rodriguez‐Chavez, 2011). Its non‐invasive, self‐collectable and low transmission risk makes WMF attractive for diagnosis of Covid‐19 (To et al. 2020). Early and quick detection of SARS‐CoV2 is of prime importance in containing its spread. Currently, most rapid antigen kits are validated for NPS specimens. In this study, we evaluated the utility of a SARS‐CoV2 antigen kit using drooled WMF samples from laboratory‐confirmed SARS‐CoV2 RT‐PCR positive patients.