Kyoto University School of Public Health, Yoshida-Konoe, Sakyo-ku, Kyoto 606-8601, Japan.
Math Biosci Eng. 2023 Jan;20(2):2530-2543. doi: 10.3934/mbe.2023118. Epub 2022 Nov 24.
With continuing emergence of new SARS-CoV-2 variants, understanding the proportion of the population protected against infection is crucial for public health risk assessment and decision-making and so that the general public can take preventive measures. We aimed to estimate the protection against symptomatic illness caused by SARS-CoV-2 Omicron variants BA.4 and BA.5 elicited by vaccination against and natural infection with other SARS-CoV-2 Omicron subvariants. We used a logistic model to define the protection rate against symptomatic infection caused by BA.1 and BA.2 as a function of neutralizing antibody titer values. Applying the quantified relationships to BA.4 and BA.5 using two different methods, the estimated protection rate against BA.4 and BA.5 was 11.3% (95% confidence interval [CI]: 0.01-25.4) (method 1) and 12.9% (95% CI: 8.8-18.0) (method 2) at 6 months after a second dose of BNT162b2 vaccine, 44.3% (95% CI: 20.0-59.3) (method 1) and 47.3% (95% CI: 34.1-60.6) (method 2) at 2 weeks after a third BNT162b2 dose, and 52.3% (95% CI: 25.1-69.2) (method 1) and 54.9% (95% CI: 37.6-71.4) (method 2) during the convalescent phase after infection with BA.1 and BA.2, respectively. Our study indicates that the protection rate against BA.4 and BA.5 are significantly lower compared with those against previous variants and may lead to substantial morbidity, and overall estimates were consistent with empirical reports. Our simple yet practical models enable prompt assessment of public health impacts posed by new SARS-CoV-2 variants using small sample-size neutralization titer data to support public health decisions in urgent situations.
随着新的 SARS-CoV-2 变体不断出现，了解人群对感染的保护比例对于公共卫生风险评估和决策至关重要，以便公众可以采取预防措施。我们旨在估计接种其他 SARS-CoV-2 奥密克戎亚变体疫苗和自然感染对 SARS-CoV-2 奥密克戎变异株 BA.4 和 BA.5 引起的有症状疾病的保护作用。我们使用逻辑模型来定义针对 BA.1 和 BA.2 引起的有症状感染的保护率，作为中和抗体滴度值的函数。使用两种不同的方法将量化的关系应用于 BA.4 和 BA.5，估计在接种第二剂 BNT162b2 疫苗 6 个月后，BA.4 和 BA.5 的保护率分别为 11.3%（95%置信区间[CI]：0.01-25.4）（方法 1）和 12.9%（95%CI：8.8-18.0）（方法 2），在接种第三剂 BNT162b2 疫苗后 2 周，BA.4 和 BA.5 的保护率分别为 44.3%（95%CI：20.0-59.3）（方法 1）和 47.3%（95%CI：34.1-60.6）（方法 2），在感染 BA.1 和 BA.2 后的康复期，BA.4 和 BA.5 的保护率分别为 52.3%（95%CI：25.1-69.2）（方法 1）和 54.9%（95%CI：37.6-71.4）（方法 2）。我们的研究表明，与之前的变体相比，BA.4 和 BA.5 的保护率明显较低，可能导致大量发病率，并且总体估计与经验报告一致。我们的简单实用模型能够使用中和抗体滴度的小样本数据快速评估新的 SARS-CoV-2 变体对公共卫生的影响，以支持紧急情况下的公共卫生决策。
