Abstract Pregnant women are at heightened risk for severe outcomes from infectious diseases like COVID-19, yet were not included in initial vaccine trials, which may contribute to low booster uptake (15% or lower). We explored the serological and cellular responses to COVID-19 mRNA booster vaccines (i.e., ancestral and BA.5) in pregnant and age-matched, non-pregnant females to identify how pregnancy affects immunity against the vaccine and novel variants. Antibodies from pregnant women were less cross-reactive to non-vaccine antigens, including XBB.1.5 and JN.1. Non-pregnant females showed greater IgG1:IgG3 ratios and neutralization against all variants. In contrast, pregnant women had lower IgG1:IgG3 ratios and neutralization but increased antibody-dependent NK cell cytokine production and neutrophil phagocytosis, especially against novel variants. Pregnancy increased memory CD4+ T cells, IFNγ production, monofunctional dominance, and fatty acid oxidation. Pregnancy may reduce the breadth, composition, and magnitude of humoral and cellular immunity, particularly in response to novel variants.
Parish et al. (Wed,) studied this question.