Background Understanding the association between the immune response and the risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has implications for forthcoming prevention strategies. We evaluated the association between antibody titers and the risk of infection for the general population during the Omicron-dominant phase. Methods This was a prospective cohort study of residents or people affiliated with institutions in Bizen City, which included 1,899 participants. We measured the titers of antibodies against SARS-CoV-2 repeatedly every 2 months from June 2022 to March 2023. Infection status was obtained from self-reported questionnaires and the official registry. We estimated risk ratios (RRs) for infection within 2 months of the date of each antibody measurement with 95% confidence intervals (CIs) based on antibody titer categories and spline functions. Results Compared with the <2,500 arbitrary unit (AU)/mL category, the 2,500–5,000, 5,000–10,000, and ≥10,000 AU/mL categories had adjusted RRs (95% CI) of 0.81 (0.61–1.08), 0.51 (0.36–0.72), and 0.41 (0.31–0.54), respectively. The spline function showed a non-linear relationship between antibody titer and risk. Conclusions Higher antibody titers were associated with a lower risk. We demonstrate the usefulness of measuring an antibody titers to determine the appropriate timing for future vaccination.

中文翻译：

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日本备前市 SARS-CoV-2 Omicron 阶段的抗体滴度和感染风险

背景 了解免疫反应与严重急性呼吸综合征冠状病毒 2 (SARS-CoV-2) 感染风险之间的关联对于未来的预防策略具有重要意义。我们评估了 Omicron 主导阶段一般人群的抗体滴度与感染风险之间的关联。方法 这是一项针对备前市居民或机构附属人员的前瞻性队列研究，其中包括 1,899 名参与者。从 2022 年 6 月到 2023 年 3 月，我们每 2 个月重复测量一次 SARS-CoV-2 抗体滴度。感染状况通过自我报告的问卷和官方登记获得。我们根据抗体滴度类别和样条函数，以 95% 置信区间 (CI) 估计每次抗体测量之日起 2 个月内的感染风险比 (RR)。结果 与 <2,500 任意单位 (AU)/mL 类别相比，2,500–5,000、5,000–10,000 和 ≥10,000 AU/mL 类别的调整 RR (95% CI) 分别为 0.81 (0.61–1.08)、0.51 (分别为 0.36–0.72) 和 0.41 (0.31–0.54)。样条函数显示抗体滴度和风险之间存在非线性关系。结论 较高的抗体滴度与较低的风险相关。我们证明了测量抗体滴度以确定未来疫苗接种的适当时机的有用性。