Chin Elizabeth T, Leidner David, Lamson Lauren, Lucas Kimberley, Studdert David M, Goldhaber-Fiebert Jeremy D, Andrews Jason R, Salomon Joshua A
medRxiv. 2022 May 27:2022.05.26.22275639. doi: 10.1101/2022.05.26.22275639.
Prisons and jails are high-risk settings for Covid-19 transmission, morbidity, and mortality. We evaluate protection conferred by prior infection and vaccination against the SARS-CoV-2 Omicron variant within the California state prison system.
We employed a test-negative design to match resident and staff cases during the Omicron wave (December 24, 2021-April 14, 2022) to controls according to a case's test-week as well as demographic, clinical, and carceral characteristics. We estimated protection against infection using conditional logistic regression, with exposure status defined by vaccination, stratified by number of mRNA doses received, and prior infection, stratified by periods before or during Delta variant predominance.
We matched 15,783 resident and 8,539 staff cases to 180,169 resident and 90,409 staff controls. Among cases, 29.7% and 2.2% were infected before or during the emergence of the Delta variant, respectively; 30.6% and 36.3% were vaccinated with two or three doses, respectively. Estimated protection from Omicron infection for two and three doses were 14.9% (95% Confidence Interval [CI], 12.3-19.7%) and 43.2% (42.2-47.4%) for those without known prior infections, 47.8% (95% CI, 46.6-52.8%) and 61.3% (95% CI, 60.7-64.8%) for those infected before the emergence of Delta, and 73.1% (95% CI, 69.8-80.1%) and 86.8% (95% CI, 82.1-92.7) for those infected during the period of Delta predominance.
A third mRNA dose provided significant, additional protection over two doses, including among individuals with prior infection. Our findings suggest that vaccination should remain a priority-even in settings with high levels of transmission and prior infection.
监狱是新冠病毒-19传播、发病和死亡的高风险场所。我们评估了加利福尼亚州监狱系统内既往感染和接种疫苗对严重急性呼吸综合征冠状病毒2（SARS-CoV-2）奥密克戎变异株的防护作用。
我们采用检测阴性设计，根据病例的检测周以及人口统计学、临床和监禁特征，将奥密克戎疫情期间（2021年12月24日至2022年4月14日）的居民和工作人员病例与对照进行匹配。我们使用条件逻辑回归估计对感染的防护作用，暴露状态由疫苗接种定义，按接种的信使核糖核酸（mRNA）剂量数量分层，既往感染按德尔塔变异株占主导之前或期间分层。
我们将15783例居民病例和8539例工作人员病例与180169例居民对照和90409例工作人员对照进行匹配。在病例中，分别有29.7%和2.2%在德尔塔变异株出现之前或期间感染；分别有30.6%和36.3%接种了两剂或三剂疫苗。对于无已知既往感染的人，两剂和三剂疫苗对奥密克戎感染的估计防护率分别为14.9%（95%置信区间[CI]，12.3 - 19.7%）和43.2%（42.2 - 47.4%）；对于在德尔塔变异株出现之前感染的人，防护率分别为47.8%（95%CI，46.6 - 52.8%）和61.3%（95%CI，60.7 - 64.8%）；对于在德尔塔变异株占主导期间感染的人，防护率分别为73.1%（95%CI，69.8 - 80.1%）和86.8%（95%CI，82.1 - 92.7%）。
第三剂mRNA疫苗比两剂疫苗提供了显著的额外防护，包括对既往感染者。我们的研究结果表明，即使在传播率高和存在既往感染的环境中，接种疫苗仍应是优先事项。
