Abstract
Breakthrough SARS-CoV-2 infections in fully vaccinated individuals are considered a consequence of waning immunity. Serum antibodies represent the most measurable outcome of vaccine-induced B cell memory. When antibodies decline, memory B cells are expected to persist and perform their function, preventing clinical disease. We investigated whether BNT162b2 mRNA vaccine induces durable and functional B cell memory in vivo against SARS-CoV-2 3, 6, and 9 months after the second dose in a cohort of health care workers (HCWs). While we observed physiological decline of SARS-CoV-2-specific antibodies, memory B cells persist and increase until 9 months after immunization. HCWs with breakthrough infections had no signs of waning immunity. In 3-4 days, memory B cells responded to SARS-CoV-2 infection by producing high levels of specific antibodies in the serum and anti-Spike IgA in the saliva. Antibodies to the viral nucleoprotein were produced with the slow kinetics typical of the response to a novel antigen.
Keywords: COVID-19; SARS-CoV-2; breakthrough infections; mRNA vaccine; memory B cells; mucosal immunity; salivary IgA; waning immunity.
【저자키워드】 COVID-19, SARS-CoV-2, mRNA vaccine, memory B cells, mucosal immunity, breakthrough infections, waning immunity, salivary IgA, 【초록키워드】 Saliva, antibody, SARS-COV-2 infection, outcome, immunization, Antigen, serum, Cohort, HCWs, IgA, mRNA, B cell memory, Health care worker, Breakthrough infection, in vivo, SARS-CoV-2-specific antibodies, memory B cell, BNT162b2 mRNA vaccine, mucosal, physiological, waning immunity, HCW, second dose, clinical disease, vaccinated individual, while, salivary, memory B, produced, investigated, specific antibody, functional, induce, producing, had no, expected, 【제목키워드】 B cell memory, Breakthrough infection, persistent, SARS-CoV-2 vaccination, functional,