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. 2022 May 11;40(22):3027-3037. doi: 10.1016/j.vaccine.2022.04.025. Epub 2022 Apr 12.
During the first half of 2021, we observed high vaccine effectiveness (VE) against SARS-CoV2-infection. The replacement of the alpha-'variant of concern' (VOC) by the delta-VOC and uncertainty about the time course of immunity called for a re-assessment.
We estimated VE against transmission of infection (VET) from Belgian contact tracing data for high-risk exposure contacts between 26/01/2021 and 14/12/2021 by susceptibility (VEs) and infectiousness of breakthrough cases (VEi) for a complete schedule of Ad26.COV2.S, ChAdOx1, BNT162b2, mRNA-1273 as well as infection-acquired and hybrid immunity. We used a multilevel Bayesian model and adjusted for personal characteristics (age, sex, household), background exposure, calendar week, VOC and time since immunity conferring-event.
VET-estimates were higher for mRNA-vaccines, over 90%, compared to viral vector vaccines: 66% and 80% for Ad26COV2.S and ChAdOx1 respectively (Alpha, 0-50 days after vaccination). Delta was associated with a 40% increase in odds of transmission and a decrease of VEs (72-64%) and especially of VEi (71-46% for BNT162b2). Infection-acquired and hybrid immunity were less affected by Delta. Waning further reduced VET-estimates: from 81% to 63% for BNT162b2 (Delta, 150-200 days after vaccination). We observed lower initial VEi in the age group 65-84 years (32% vs 46% in the age group 45-64 years for BNT162b2) and faster waning. Hybrid immunity waned slower than vaccine-induced immunity.
VEi and VEs-estimates, while remaining significant, were reduced by Delta and waned over time. We observed faster waning in the oldest age group. We should seek to improve vaccine-induced protection in older persons and those vaccinated with viral-vector vaccines.
在 2021 年上半年，我们观察到针对 SARS-CoV2 感染的高疫苗有效性（VE）。阿尔法“关注变体”（VOC）被德尔塔 VOC 取代，以及对免疫持续时间的不确定性，这都需要重新评估。
我们通过比利时高危接触者追踪数据，估算了 2021 年 1 月 26 日至 12 月 14 日期间，针对突破性感染的传播疫苗有效性（VET），以及针对腺病毒载体疫苗（Ad26.COV2.S、ChAdOx1）、信使 RNA 疫苗（BNT162b2、mRNA-1273）的完全接种方案，感染获得性和混合免疫的易感性（VE）和传染性（VEi）。我们使用多层次贝叶斯模型，并根据个人特征（年龄、性别、家庭）、背景暴露、日历周、VOC 和免疫事件发生后的时间进行调整。
与病毒载体疫苗相比，mRNA 疫苗的 VET 估计值更高，超过 90%：Ad26.COV2.S 和 ChAdOx1 分别为 66%和 80%（阿尔法，接种后 0-50 天）。德尔塔与传播几率增加 40%以及 VE 降低（BNT162b2 为 72-64%，特别是 VEi 降低 71-46%）有关。感染获得性和混合免疫受德尔塔的影响较小。进一步衰减降低了 VET 估计值：从 BNT162b2 的 81%降至 63%（德尔塔，接种后 150-200 天）。我们观察到 65-84 岁年龄组初始 VEi 较低（BNT162b2 为 32%，45-64 岁年龄组为 46%），衰减速度较快。混合免疫衰减速度比疫苗诱导的免疫慢。
尽管 VEi 和 VE 估计值仍然显著，但它们被德尔塔削弱，并随着时间的推移而衰减。我们观察到最年长的年龄组衰减速度较快。我们应该寻求提高老年人和接种病毒载体疫苗人群的疫苗诱导保护。
