Following the original severe acute respiratory syndrome coronavirus 2 strain (Wuhan-Hu-1) in December 2019, the Delta variant in May 2021 and the Omicron variant in December 2021 were classified as variants of concern. The pandemic has been ongoing for more than two years, and the three-dose vaccination rate has reached approximately 50% in Korea. We analyzed anti-S antibodies (Abs) and neutralizing Abs (NAbs) in 32 healthcare workers at a university hospital, focusing on the first to third doses of ChAdOx1-ChAdOx1-BNT162b2, which is the most common vaccination regimen in Korea. Antibodies were analyzed at eight time points according to the vaccine regimen. The first to third doses of ChAdOx1-ChAdOx1-BNT162b2 produced high Ab concentrations; NAb concentrations after the third dose were predicted to remain high for a longer period than those after the first and second doses. The effectiveness of a second dose of ChAdOx1 in the real world was demonstrated by analyzing samples collected during an outbreak that occurred in the study period, 4-5 months after the second dose. The relative risk ratio was 88.0%, and the efficacy of the second ChAdOx1 dose was 12.0% (P<0.05). Therefore, maintaining appropriate Ab concentrations through regular vaccination will help protect against coronavirus disease-19.

中文翻译：

---

卫生保健工作者接种两剂 ChAdOx1 后第三剂 BNT162b2 mRNA 疫苗的免疫原性：一项前瞻性纵向研究。

继 2019 年 12 月最初的严重急性呼吸系统综合征冠状病毒 2 株（Wuhan-Hu-1）之后，2021 年 5 月的 Delta 变体和 2021 年 12 月的 Omicron 变体被列为关注变体。大流行已经持续了两年多，韩国的三剂疫苗接种率已达到约50%。我们分析了一家大学医院 32 名医护人员的抗 S 抗体 (Abs) 和中和抗体 (NAbs)，重点关注第一至第三剂 ChAdOx1-ChAdOx1-BNT162b2，这是韩国最常见的疫苗接种方案。根据疫苗方案在八个时间点分析抗体。第一至第三剂 ChAdOx1-ChAdOx1-BNT162b2 产生高抗体浓度；与第一次和第二次给药后相比，预计第三次给药后的 NAb 浓度将在更长的时间内保持较高水平。第二剂 ChAdOx1 在现实世界中的有效性通过分析在研究期间（第二剂后 4-5 个月）发生的暴发期间收集的样本来证明。相对风险比为 88.0%，第二剂 ChAdOx1 的疗效为 12.0%（P <0.05）。因此，通过定期接种疫苗来维持适当的抗体浓度将有助于预防冠状病毒病 19。