Department of Epidemiology and public health, Sciensano, Juliette Wytsmansstraat 14, 1000 Brussel, Belgium.
Department of Epidemiology and public health, Sciensano, Juliette Wytsmansstraat 14, 1000 Brussel, Belgium.
Vaccine. 2023 May 11;41(20):3292-3300. doi: 10.1016/j.vaccine.2023.03.069. Epub 2023 Apr 5.
Vaccine effectiveness against transmission (VET) of SARS-CoV-2-infection can be estimated from secondary attack rates observed during contact tracing. We estimated VET, the vaccine-effect on infectiousness of the index case and susceptibility of the high-risk exposure contact (HREC).
We fitted RT-PCR-test results from HREC to immunity status (vaccine schedule, prior infection, time since last immunity-conferring event), age, sex, calendar week of sampling, household, background positivity rate and dominant VOC using a multilevel Bayesian regression-model. We included Belgian data collected between January 2021 and January 2022.
For primary BNT162b2-vaccination we estimated initial VET at 96% (95%CI 95-97) against Alpha, 87% (95%CI 84-88) against Delta and 31% (95%CI 25-37) against Omicron. Initial VET of booster-vaccination (mRNA primary and booster-vaccination) was 87% (95%CI 86-89) against Delta and 68% (95%CI 65-70) against Omicron. The VET-estimate against Delta and Omicron decreased to 71% (95%CI 64-78) and 55% (95%CI 46-62) respectively, 150-200 days after booster-vaccination. Hybrid immunity, defined as vaccination and documented prior infection, was associated with durable and higher or comparable (by number of antigen exposures) protection against transmission.
While we observed VOC-specific immune-escape, especially by Omicron, and waning over time since immunization, vaccination remained associated with a reduced risk of SARS-CoV-2-transmission.
通过接触者追踪中观察到的二次攻击率，可以估计针对 SARS-CoV-2 感染的疫苗有效性（VET）。我们估计了 VET、指数病例的传染性疫苗效应和高风险接触者（HREC）的易感性。
我们使用多级贝叶斯回归模型，根据疫苗接种计划、既往感染、上次免疫事件后的时间、年龄、性别、采样日历周、家庭、背景阳性率和优势 VOC 状态，拟合 HREC 的 RT-PCR 检测结果。我们纳入了 2021 年 1 月至 2022 年 1 月期间在比利时收集的数据。
对于 BNT162b2 初级疫苗接种，我们估计对 Alpha 的初始 VET 为 96%（95%CI 95-97），对 Delta 为 87%（95%CI 84-88），对 Omicron 为 31%（95%CI 25-37）。mRNA 初级和加强疫苗接种的加强疫苗接种的初始 VET 对 Delta 和 Omicron 的分别为 87%（95%CI 86-89）和 68%（95%CI 65-70）。加强疫苗接种后 150-200 天，对 Delta 和 Omicron 的 VET 估计值分别降至 71%（95%CI 64-78）和 55%（95%CI 46-62）。定义为接种和记录的既往感染的混合免疫与持久和更高或可比（按抗原暴露次数计算）的传播保护相关。
虽然我们观察到针对特定变异株的免疫逃逸，尤其是 Omicron 株，且随着时间的推移免疫效果减弱，但疫苗接种仍与降低 SARS-CoV-2 传播风险相关。
