"The observed extended presence of vaccine mRNA and spike protein in vaccinee LN GCs for up to 2 months after vaccination was in contrast to rare foci of viral spike protein in COVID-19 patient LNs. We hypothesize that the abundant spike antigen in the GCs of mRNA vaccine recipient LNs may contribute to the increased breadth of viral variant RBD binding by IgG seen after vaccination, potentially due to high antigen concentrations stimulating B cells with lower affinity for Wuhan-Hu-1 spike epitopes and better binding to variant epitopes."