Mucosal immune responses to SARS-CoV-2 infection and COVID-19 vaccination
Paul, Mathew J Hudda, Mohammed T Pallett, Scott Groppelli, Elisabetta Boariu, Eugenia Finardi, Nicole Falci Wake, Rachel Sofat, Nidhi Biddle, Kathryn Koushesh, Soraya
Paul, Mathew J
Hudda, Mohammed T
Pallett, Scott
Groppelli, Elisabetta
Boariu, Eugenia
Finardi, Nicole Falci
Wake, Rachel
Sofat, Nidhi
Biddle, Kathryn
Koushesh, Soraya
Affiliation
City St. George's University of London; Dasman Institute; University Hospitals Birmingham NHS Foundation Trust; St. George's University Hospitals NHS Foundation Trust; Kings College London
Other Contributors
Publication date
2025-04-30
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Collections
Research Projects
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Abstract
SARS-CoV-2 continues to circulate in the community. We hypothesise that mucosal immunity is required to prevent continuing viral acquisition and transmission.
Objectives: To determine whether SARS-CoV-2 infection or vaccination elicits specific neutralising antibodies in saliva, and to assess the longevity of protection.
Methods: Initially, 111 COVID-19 convalescent participants were recruited, 11-369 days after diagnosis. Saliva and blood samples were assayed for antibodies specific for Spike protein, Receptor Binding Domain and Nucleoprotein. In a second cohort, 123 participants were recruited. Saliva and serum antibodies to the same antigens were assayed before and after their first and second COVID-19 vaccinations, with 150 day follow up.
Results: Natural infection induces and boosts IgA and IgG in oral fluid and serum; vaccination does not induce or boost specific saliva IgA; IgG can be found in saliva after vaccination, but only when serum IgG concentrations are high; IgA is important for SARS-CoV-2 neutralisation activity by oral fluid, but there can also be contributions from serum IgG and other factors.
Conclusions: New COVID-19 vaccines should target both systemic and mucosal immunity, to establish a first line of immune defence at the mucosal barrier. This would benefit vulnerable patient populations and may help to eradicate SARS-CoV-2 circulation.
Citation
Paul MJ, Hudda MT, Pallett S, Groppelli E, Boariu E, Finardi NF, Wake R, Sofat N, Biddle K, Koushesh S, Dwyer-Hemmings L, Cook R, Ma JK. Mucosal immune responses to SARS-CoV-2 infection and COVID-19 vaccination. Vaccine. 2025 May 22;56:127175. doi: 10.1016/j.vaccine.2025.127175. Epub 2025 Apr 30.
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Article