ASTAR Infectious Diseases Labs (ASTAR ID Labs), Agency for Science, Technology and Research (ASTAR), Singapore, Singapore.
Singapore Immunology Network, Agency for Science, Technology and Research (ASTAR), Singapore, Singapore.
Front Immunol. 2022 Nov 14;13:1031852. doi: 10.3389/fimmu.2022.1031852. eCollection 2022.
The emergence of new SARS-CoV-2 variants, such as the more transmissible Delta and Omicron variants, has raised concerns on efficacy of the COVID-19 vaccines. Here, we examined the waning of antibody responses against different variants following primary and booster vaccination. We found that antibody responses against variants were low following primary vaccination. The antibody response against Omicron was almost non-existent. Efficient boosting of antibody response against all variants, including Omicron, was observed following a third dose. The antibody response against the variants tested was significantly higher at one month following booster vaccination, compared with two months following primary vaccination, for all individuals, including the low antibody responders identified at two months following primary vaccination. The antibody response, for all variants tested, was significantly higher at four months post booster than at five months post primary vaccination, and the proportion of low responders remained low (6-11%). However, there was significant waning of antibody response in more than 95% of individuals at four months, compared to one month following booster. We also observed a robust memory B cell response following booster, which remained higher at four months post booster than prior to booster. However, the memory B cell responses were on the decline for 50% of individuals at four months following booster. Similarly, while the T cell response is sustained, at cohort level, at four months post booster, a substantial proportion of individuals (18.8 - 53.8%) exhibited T cell response at four months post booster that has waned to levels below their corresponding levels before booster. The findings show an efficient induction of immune response against SARS-CoV-2 variants following booster vaccination. However, the induced immunity by the third BNT162b2 vaccine dose was transient. The findings suggest that elderly individuals may require a fourth dose to provide protection against SARS-CoV-2.
新的 SARS-CoV-2 变体的出现，如更具传染性的 Delta 和 Omicron 变体，引起了人们对 COVID-19 疫苗效力的担忧。在这里，我们研究了初次接种和加强接种后针对不同变体的抗体反应下降情况。我们发现，初次接种后，针对变体的抗体反应较低。对 Omicron 的抗体反应几乎不存在。第三剂接种后，观察到针对所有变体（包括 Omicron）的抗体反应有效增强。与初次接种后两个月相比，加强接种后一个月，所有个体（包括初次接种后两个月确定的低抗体应答者）针对测试变体的抗体反应显著更高。与初次接种后五个月相比，加强接种后四个月针对所有变体的抗体反应显著更高，低应答者的比例仍然较低（6-11%）。然而，与加强接种后一个月相比，超过 95%的个体的抗体反应在四个月时显著下降。我们还观察到加强接种后记忆 B 细胞反应增强，加强接种后四个月仍高于加强接种前。然而，在加强接种后四个月，有 50%的个体的记忆 B 细胞反应呈下降趋势。同样，虽然 T 细胞反应在队列水平上持续存在，但在加强接种后四个月，相当比例的个体（18.8-53.8%）的 T 细胞反应下降到低于加强接种前的水平。这些发现表明，加强接种后能够有效地诱导针对 SARS-CoV-2 变体的免疫反应。然而，第三剂 BNT162b2 疫苗诱导的免疫是短暂的。研究结果表明，老年人可能需要第四剂疫苗来提供针对 SARS-CoV-2 的保护。
