Abstract

The present study aimed to clarify unusual total antibody kinetics in three female individuals observed during longitudinal monitoring of antibody response to BNT162b2 COVID-19 vaccine in 54 healthy volunteers. Total and IgG antibodies against the SARS-CoV-2 spike glycoprotein were measured using Roche and Abbott quantitative assays, respectively, a day before and 8, 71, 135 and 217 days after the second dose. Samples showing unusual kinetics were additionally tested with Beckman Coulter and Euroimmun IgG assays, as well as IgA assay. Antibody levels peaked 8 days after the second dose (total:2769 U/mL; IgG:20022 AU/mL) and declined to 611 U/mL (total) and 783 AU/mL (IgG), after 217 days. A delayed increase of total but not IgG antibodies evidenced in three females, was in two cases coupled with an increase in IgA antibodies. This study identified a previously unknown contribution of anti-SARS-CoV-2 IgA antibodies to a delayed total antibody increase in a subgroup of vaccinated individuals. It also emphasizes that different commercially available serological assays do not provide uniform information about the post-vaccination immune status and that thorough understanding the assays’ features is crucial for the proper interpretation of antibody response monitoring.

摘要

本研究旨在阐明在纵向监测 54 名健康志愿者对 BNT162b2 COVID-19 疫苗的抗体反应期间观察到的三名女性个体的异常总抗体动力学。在第二次给药的前一天和 8、71、135 和 217 天，分别使用罗氏和雅培定量测定法测量了针对 SARS-CoV-2 刺突糖蛋白的总抗体和 IgG 抗体。还用 Beckman Coulter 和 Euroimmun IgG 测定以及 IgA 测定对显示异常动力学的样品进行了额外测试。抗体水平在第二次给药后 8 天达到峰值（总量：2769 U/mL；IgG：20022 AU/mL），并在 217 天后降至 611 U/mL（总量）和 783 AU/mL (IgG)。在三名女性中证实了总抗体而非 IgG 抗体的延迟增加，在两个案例中与 IgA 抗体的增加有关。这项研究确定了以前未知的抗 SARS-CoV-2 IgA 抗体对疫苗接种个体亚组延迟总抗体增加的贡献。它还强调，不同的市售血清学检测不能提供关于疫苗接种后免疫状态的统一信息，并且彻底了解检测的特征对于正确解释抗体反应监测至关重要。