The development of vaccines to prevent SARS-CoV-2 infection has mainly relied on the induction of neutralizing antibodies (nAbs) to the Spike protein of SARS-CoV-2, but there is growing evidence that T cell immune response can contribute to protection as well. In this study, an anti-receptor binding domain (RBD) antibody assay and an INFγ-release assay (IGRA) were used to detect humoral and cellular responses to the Pfizer-BioNTech BNT162b2 vaccine in three separate cohorts of COVID-19-naïve patients: 108 healthcare workers (HCWs), 15 elderly people, and 5 autoimmune patients treated with immunosuppressive agents. After the second dose of vaccine, the mean values of anti-RBD antibodies (Abs) and INFγ were 123.33 U/mL (range 27.55–464) and 1513 mIU/mL (range 145–2500) in HCWs and 210.7 U/mL (range 3–500) and 1167 mIU/mL (range 83–2500) in elderly people. No correlations between age and immune status were observed. On the contrary, a weak but significant positive correlation was found between INFγ and anti-RBD Abs values (rho = 0.354, p = 0.003). As to the autoimmune cohort, anti-RBD Abs were not detected in the two patients with absent peripheral CD19⁺B cells, despite high INFγ levels being observed in all 5 patients after vaccination. Even though the clinical relevance of T cell response has not yet been established as a correlate of vaccine-induced protection, IGRA testing has showed optimal sensitivity and specificity to define vaccine responders, even in patients lacking a cognate antibody response to the vaccine.

预防 SARS-CoV-2 感染的疫苗开发主要依赖于诱导针对 SARS-CoV-2 刺突蛋白的中和抗体 (nAb)，但越来越多的证据表明，T 细胞免疫反应可以有助于保护出色地。在这项研究中，使用抗受体结合域 (RBD) 抗体测定和 INFγ 释放测定 (IGRA) 来检测三组不同的未接触过 COVID-19 的患者对辉瑞 BioNTech BNT162b2 疫苗的体液和细胞反应：108 名医护人员 (HCW)、15 名老年人和 5 名接受免疫抑制剂治疗的自身免疫患者。第二剂疫苗接种后，医护人员的抗 RBD 抗体 (Abs) 和 INFγ 的平均值分别为 123.33 U/mL（范围 27.55-464）和 1513 mIU/mL（范围 145-2500），而 210.7 U/mL（范围 145-2500）。老年人的范围 3-500）和 1167 mIU/mL（范围 83-2500）。没有观察到年龄和免疫状态之间的相关性。相反，INFγ 和抗 RBD Abs 值之间存在微弱但显着的正相关性（ rho = 0.354， p = 0.003）。至于自身免疫队列，尽管在接种疫苗后所有 5 名患者中均观察到高 INFγ 水平，但在两名外周 CD19 ⁺ B 细胞缺失的患者中未检测到抗 RBD 抗体。尽管 T 细胞反应的临床相关性尚未确定为疫苗诱导保护的相关性，但 IGRA 测试已显示出定义疫苗反应者的最佳敏感性和特异性，即使是在对疫苗缺乏同源抗体反应的患者中。