AUTHOR=Conti Maria Giulia , Piano Mortari Eva , Nenna Raffaella , Pierangeli Alessandra , Sorrentino Leonardo , Frasca Federica , Petrarca Laura , Mancino Enrica , Di Mattia Greta , Matera Luigi , Fracella Matteo , Albano Christian , Scagnolari Carolina , Capponi Martina , Cinicola Bianca , Carsetti Rita , Midulla Fabio TITLE=SARS-CoV-2–specific mucosal immune response in vaccinated versus infected children JOURNAL=Frontiers in Cellular and Infection Microbiology VOLUME=14 YEAR=2024 URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2024.1231697 DOI=10.3389/fcimb.2024.1231697 ISSN=2235-2988 ABSTRACT=

The anti-COVID-19 intramuscular vaccination induces a strong systemic but a weak mucosal immune response in adults. Little is known about the mucosal immune response in children infected or vaccinated against SARS-CoV-2. We found that 28% of children had detectable salivary IgA against SARS-CoV-2 even before vaccination, suggesting that, in children, SARS-CoV-2 infection may be undiagnosed. After vaccination, only receptor-binding domain (RBD)–specific IgA1 significantly increased in the saliva. Conversely, infected children had significantly higher salivary RBD-IgA2 compared to IgA1, indicating that infection more than vaccination induces a specific mucosal immune response in children. Future efforts should focus on development of vaccine technologies that also activate mucosal immunity.