Vaccination against SARS-CoV-2 protects from infection and improves clinical outcomes in breakthrough infections, likely reflecting residual vaccine-elicited immunity and recall of immunological memory. Here, we define the early kinetics of spike-specific humoral and cellular immunity after vaccination of seropositive individuals and after Delta or Omicron breakthrough infection in vaccinated individuals. Early longitudinal sampling revealed the timing and magnitude of recall, with the phenotypic activation of B cells preceding an increase in neutralizing antibody titers. While vaccination of seropositive individuals resulted in robust recall of humoral and T cell immunity, recall of vaccine-elicited responses was delayed and variable in magnitude during breakthrough infections and depended on the infecting variant of concern. While the delayed kinetics of immune recall provides a potential mechanism for the lack of early control of viral replication, the recall of antibodies coincided with viral clearance and likely underpins the protective effects of vaccination against severe COVID-19.

针对 SARS-CoV-2 的疫苗接种可防止感染并改善突破性感染的临床结果，这可能反映了疫苗引发的残留免疫力和免疫记忆的回忆。在这里，我们定义了在血清阳性个体接种疫苗后以及接种疫苗的个体中 Delta 或 Omicron 突破性感染后尖峰特异性体液和细胞免疫的早期动力学。早期纵向采样揭示了回忆的时间和幅度，B 细胞的表型激活先于中和抗体滴度的增加。虽然血清阳性个体的疫苗接种导致体液免疫和 T 细胞免疫的强烈回忆，但在突破性感染期间，疫苗引起的反应的回忆被延迟并且幅度可变，并且取决于所关注的感染变体。