An ELISA‐Based Method to Measure Mucosal Antibody Responses Against SARS‐CoV‐2 in Human Saliva

The primary mode of transmission for severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is infection of the respiratory tract through droplets and/or aerosols. Therefore, immune responses at respiratory mucosal surfaces play a significant role in the prevention of infection. Greater emphasis is now being placed on mucosal immunity induced by exposure to SARS‐CoV‐2 antigens through infection or vaccination. In concert with cellular immunity, humoral responses at mucosal surfaces, especially the secretory version of immunoglobulin A (sIgA), can be instrumental in preventing respiratory infections. A better understanding of mucosal immune responses can further our knowledge of immunity to SARS‐CoV‐2 and help inform vaccine design. Here we describe a detailed protocol for an in vitro assay based on the enzyme‐linked immunosorbent assay (ELISA) to assess mucosal antibody response to SARS‐CoV‐2 spike protein in human saliva.