Antibodies on mucosal surfaces of the upper respiratory tract have been shown to be important for protection from infection with SARS-CoV-2. Here we investigate the induction of serum IgG, saliva IgG, and saliva sIgA after COVID-19 mRNA booster vaccination or breakthrough infections.
Keywords: SARS-CoV-2; booster vaccination; breakthrough infection; mRNA vaccine; sIgA; saliva; spike.