Direction régionale de santé publique de Montréal, Montreal, Quebec, Canada.
Canadian Field Epidemiology Program, Public Health Agency of Canada, Canada.
JAMA Netw Open. 2022 Feb 1;5(2):e2147042. doi: 10.1001/jamanetworkopen.2021.47042.
Given limited COVID-19 vaccine availability early in the pandemic, optimizing immunization strategies was of paramount importance. Ring vaccination has been used successfully to control transmission of other airborne respiratory viruses.
To assess the association of a ring vaccination intervention on COVID-19 spread in the initial epicenter of SARS-CoV-2 Alpha variant transmission in Montreal, Canada.
DESIGN, SETTING, AND PARTICIPANTS: This cohort study compared COVID-19 daily disease risk in 3 population-based groups of neighborhoods in Montreal, Canada, defined by their intervention-specific vaccine coverage at the neighborhood level: the primary intervention group (500 or more vaccinated persons per 10 000 persons), secondary intervention group (95 to 499), and control group (0 to 50). The groups were compared within each of 3 time periods: before intervention (December 1, 2020, to March 16, 2021), during and immediately after intervention (March 17 to April 17, 2021), and 3 weeks after the intervention midpoint (April 18 to July 18, 2021). Data were analyzed between June 2021 and November 2021.
Vaccination targeted parents and teachers of children attending the 32 schools and 48 childcare centers in 2 adjacent neighborhoods with highest local transmission (case counts) of Alpha variant shortly after its introduction. Participants were invited to receive 1 dose of mRNA vaccine between March 22 and April 9, 2021 (before vaccine was available to these age groups).
COVID-19 risk in 3 groups of neighborhoods based on intervention-specific vaccine coverage.
A total of 11 794 residents were immunized, with a mean (SD) age of 43 (8) years (range, 16-93 years); 5766 participants (48.9%) lived in a targeted neighborhood, and 9784 (83.0%) were parents. COVID-19 risk in the primary intervention group was significantly higher than in the control group before (unadjusted risk ratio [RR], 1.58; 95% CI 1.52-1.65) and during (RR, 1.63; 95% CI, 1.52-1.76) intervention, and reached a level similar to the other groups in the weeks following the intervention (RR, 1.03; 95% CI, 0.94-1.12). A similar trend was observed when restricting to SARS-CoV-2 variants and persons aged 30 to 59 years (before: RR, 1.72; 95% CI, 1.63-1.83 vs after: RR, 1.01; 95% CI, 0.88-1.17).
Our findings show that ring vaccination was associated with a reduction in COVID-19 risk in areas with high local transmission of Alpha variant shortly after its introduction. Ring vaccination may be considered as an adjunct to mass immunization to control transmission in specific areas, based on local epidemiology.
在大流行早期，由于 COVID-19 疫苗的供应有限，因此优化免疫策略至关重要。环疫苗接种已成功用于控制其他空气传播呼吸道病毒的传播。
评估在加拿大蒙特利尔 SARS-CoV-2 Alpha 变体传播的最初中心进行的环疫苗接种干预对 COVID-19 传播的影响。
设计、地点和参与者：本队列研究比较了加拿大蒙特利尔的 3 个基于人群的社区的 COVID-19 每日疾病风险，这些社区根据社区层面的特定疫苗接种覆盖率进行定义：主要干预组（每 10000 人中有 500 人或以上接种疫苗）、次要干预组（95 至 499）和对照组（0 至 50）。在每个 3 个时间段内比较了这些组：干预前（2020 年 12 月 1 日至 2021 年 3 月 16 日）、干预期间和干预后立即（2021 年 3 月 17 日至 4 月 17 日）以及干预中点后 3 周（2021 年 4 月 18 日至 7 月 18 日）。数据分析于 2021 年 6 月至 2021 年 11 月进行。
疫苗接种针对的是在 Alpha 变体引入后不久当地传播（病例数）最高的 2 个相邻社区的 32 所学校和 48 所日托中心的儿童的父母和教师。参与者被邀请在 2021 年 3 月 22 日至 4 月 9 日之间接种 1 剂 mRNA 疫苗（在此年龄组可获得疫苗之前）。
基于干预特定疫苗接种覆盖率的 3 个社区组的 COVID-19 风险。
共有 11794 名居民接受了免疫接种，平均（SD）年龄为 43（8）岁（范围，16-93 岁）；5766 名参与者（48.9%）居住在目标社区，9784 名（83.0%）是父母。在干预前（未调整的风险比 [RR]，1.58；95%CI，1.52-1.65）和干预期间（RR，1.63；95%CI，1.52-1.76），主要干预组的 COVID-19 风险明显高于对照组，并且在干预后几周内达到与其他组相似的水平（RR，1.03；95%CI，0.94-1.12）。当限制为 SARS-CoV-2 变体和 30 至 59 岁的人时，也观察到类似的趋势（干预前：RR，1.72；95%CI，1.63-1.83 与干预后：RR，1.01；95%CI，0.88-1.17）。
我们的研究结果表明，环疫苗接种与在 Alpha 变体引入后不久当地传播高的地区 COVID-19 风险降低有关。基于当地流行病学，可以考虑将环疫苗接种作为大规模免疫接种的辅助手段，以控制特定地区的传播。
