Elevated mucosal antibody responses against SARS-CoV-2 are correlated with lower viral load and faster decrease in systemic COVID-19 symptoms

Fröberg, J.; Gillard, J.; Philipsen, R.; Lanke, K.; Rust, J.; van Tuijl, D.; Bousema, T.; Simonetti, E.; van der Gaast-de Jongh, C.; Bos, M.; van Kuppeveld, F. J. M.; Bosch, B. J.; Nabuurs-Franssen, M.; van der Geest-Blankert, N.; van Daal, C.; Huynen, M. A.; de Jonge, M. I.; Diavatopoulos, D. A.

Mucosal antibodies play a key role in protection against SARS-CoV-2 exposure, but their role during primary infection is not well understood. We assessed mucosal antibody responses during primary infection with SARS-CoV-2 and examined their relationship with viral load and clinical symptoms. Elevated mucosal IgM was associated with lower viral load. RBD and viral spike protein-specific mucosal antibodies were correlated with decreases in systemic symptoms, while older age was associated with an increase in respiratory symptoms. Up to 42% of household contacts developed SARS-CoV-2-specific mucosal antibodies, including children, indicating high transmission rates within households in which children might play an important role.