Immunogenicity and memory B-cell potency induced by an inactivated COVID-19 vaccine in pregnant women

During pregnancy, profound immunological, hormonal, and metabolic adaptations occur to support fetal development. The impact of pregnancy on vaccine-induced immunity remains incompletely characterized, as previous studies have primarily focused on serological antibody levels but not immune memory. Immune memory is critical for vaccine effectiveness, but effect of pregnancy on immune memory remain unknown. In addition, the memory B cell response profile induced by inactivated coronavirus disease 2019 (COVID-19) vaccines in pregnant women remains unclear. This study comprehensively investigated the serological responses and memory B cell response induced by an inactivated COVID-19 vaccine in pregnant women. The results demonstrated that while pregnant women and non-pregnant women of childbearing age showed comparable serological antibody levels, vaccine-induced monoclonal antibodies (mAbs) from pregnant women exhibited significantly lower binding potency to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein and its segments and weaker neutralizing potency and breadth than those from non-pregnant women. Vaccine-induced mAbs from pregnant women were derived predominantly from IGHV3-30, whereas those from non-pregnant women were derived diverse germline genes. Most of mAbs from pregnant women targeted the receptor-binding domain (RBD) (40.9%) and S2 domain (31.8%), whereas most of mAbs from non-pregnant women targeted the RBD (51.3%) and N-terminal domain (30.8%). These findings suggested that pregnancy may impair the potency of vaccine-induced memory B cells. These insights may be valuable for the development of vaccination strategies for pregnant women.