Department of Molecular Medicine, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Bergamo, Italy.
Front Immunol. 2023 Feb 28;14:1123158. doi: 10.3389/fimmu.2023.1123158. eCollection 2023.
We examined the immune response in subjects previously infected with SARS-CoV2 and infection-naïve 9 months after primary 2-dose COVID-19 mRNA vaccination and 3 months after the booster dose in a longitudinal cohort of healthcare workers. Nine months after primary vaccination, previously infected subjects exhibited higher residual antibody levels, with significant neutralizing activity against distinct variants compared to infection-naïve subjects. The higher humoral response was associated with higher levels of receptor binding domain (RBD)-specific IgG and IgA memory B cells. The booster dose increased neither neutralizing activity, nor the B and T cell frequencies. Conversely, infection-naïve subjects needed the booster to achieve comparable levels of neutralizing antibodies as those found in previously infected subjects after primary vaccination. The neutralizing titer correlated with anti-RBD IFNγ producing T cells, in the face of sustained B cell response. Notably, pre-pandemic samples showed high Omicron cross-reactivity. These data show the importance of the booster dose in reinforcing immunological memory and increasing circulating antibodies in infection-naïve subjects.
我们在一项医护人员的纵向队列研究中，检测了在初次接种两剂 COVID-19 mRNA 疫苗后 9 个月、加强针接种后 3 个月时，既往感染过 SARS-CoV-2 且无感染史的受试者的免疫应答。与无感染史的受试者相比，初次接种 9 个月后，既往感染过的受试者表现出更高的残留抗体水平，对不同变异体具有显著的中和活性。更高的体液反应与更高水平的受体结合域（RBD）特异性 IgG 和 IgA 记忆 B 细胞有关。加强针接种既没有增加中和活性，也没有增加 B 和 T 细胞频率。相反，无感染史的受试者需要加强针来达到与初次接种后既往感染过的受试者相当的中和抗体水平。中和滴度与抗 RBD IFNγ 产生的 T 细胞相关，同时 B 细胞反应持续存在。值得注意的是，大流行前的样本显示出对奥密克戎的高交叉反应性。这些数据表明加强针接种在增强无感染史受试者的免疫记忆和增加循环抗体方面的重要性。
