Objective

To assess the antibody response in non-immunocompromised adults after two doses of BNT162b2.

Methods

Prospective, single-centre observational study in non-immunocompromised adults aged 18 years or more who received two doses of BNT162b2. The study contemplates analyses of serum samples collected 1.5, 3, 6, 9 and 12 months after the second dose of BNT162b2; results of the 1.5- and 3-month time-points are presented in this report. Antibodies against the receptor binding domain of the S1 subunit of the spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (anti-RBD antibodies) were measured using a commercial quantitative immunoassay. A threshold of 4160 AU/mL (corresponding to an ID₅₀ of 1:250) was used as surrogate marker for serum neutralizing activity.

Results

Of 273 hospital workers who received two doses of BNT162b2, 260 (95%) agreed to participate in the study; 2/260 (0.8%) were excluded because of immunocompromised conditions. At the time of this report, 230/258 (89%) participants (mean age 46.0 years (SD 11.4 years); 143/230 (62%) female; 87/230 (38%) male) had completed 3 months of follow up after the second dose of BNT162b2. Thirty-six (16%) of the 230 had documented mild SARS-CoV-2 infection before receiving the first dose of BNT162b2. Median (interquartile range (IQR)) anti-RBD titres 1.5 months after vaccination were 9356 (5844–16 876) AU/mL; 3 months after vaccination, median anti-RBD titres had declined to 3952 (2190–8561) AU/mL (p < 0.001). Of 199/230 (86.5%) participants who had anti-RBD titres above 4160 AU/mL 1.5 months after the second dose of BNT162b2, only 95/230 (41%) maintained anti-RBD titres above this level 3 months after vaccination (p < 0.001).

Conclusions

The decline of anti-RBD antibodies 3 months after the second dose of BNT162b2 is of concern because it raises the possibility of a short-lived humoral immunity after vaccination. Booster doses of BNT162b2 might be required to maintain high titres of anti-RBD antibodies over time.

中文翻译：

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在非免疫功能低下的成年人中，两剂 BNT162b2 3 个月后抗体滴度下降

客观的

评估两剂 BNT162b2 后非免疫功能低下成人的抗体反应。

方法

在接受两剂 BNT162b2 的 18 岁或以上非免疫功能低下的成年人中进行的前瞻性、单中心观察性研究。该研究考虑对在第二剂 BNT162b2 后 1.5、3、6、9 和 12 个月收集的血清样本进行分析；本报告提供了 1.5 个月和 3 个月时间点的结果。使用商业定量免疫测定法测量针对严重急性呼吸综合征冠状病毒 2 (SARS-CoV-2) 刺突蛋白 S1 亚基受体结合域的抗体（抗 RBD 抗体）。4160 AU/mL 的阈值（对应于1:250的 ID ₅₀）用作血清中和活性的替代标记。

结果

在接受两剂 BNT162b2 的 273 名医院工作人员中，260 名 (95%) 同意参与该研究；2/260 (0.8%) 由于免疫功能低下而被排除在外。在撰写本报告时，230/258 (89%) 参与者（平均年龄 46.0 岁（SD 11.4 岁）；143/230（62%）女性；87/230（38%）男性）已完成 3 个月的随访在第二剂 BNT162b2 后上升。在接受第一剂 BNT162b2 之前，230 人中有 36 人（16%）记录了轻度 SARS-CoV-2 感染。接种疫苗后 1.5 个月的中位（四分位距 (IQR)）抗 RBD 滴度为 9356 (5844–16 876) AU/mL；接种疫苗后 3 个月，中位抗 RBD 滴度下降至 3952 (2190–8561) AU/mL (p < 0.001)。在第二剂 BNT162b2 后 1.5 个月内，199/230 (86.5%) 名参与者的抗 RBD 滴度高于 4160 AU/mL，

结论

第二剂 BNT162b2 后 3 个月抗 RBD 抗体的下降值得关注，因为它增加了疫苗接种后短期体液免疫的可能性。随着时间的推移，可能需要加强剂量的 BNT162b2 来维持高滴度的抗 RBD 抗体。