BACKGROUND AND OBJECTIVES Understanding the real-world impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mitigation measures, particularly vaccination, in children and adolescents in congregate settings remains important. We evaluated protection against SARS-CoV-2 infection using school-based testing data. METHODS Using data from Utah middle- and high-school students participating in school-wide antigen testing in January 2022 during omicron (BA.1) variant predominance, log binomial models were fit to estimate the protection of previous SARS-CoV-2 infection and coronavirus disease 2019 vaccination against SARS-CoV-2 infection. RESULTS Among 17 910 students, median age was 16 years (range: 12-19), 16.7% had documented previous SARS-CoV-2 infection; 55.6% received 2 vaccine doses with 211 median days since the second dose; and 8.6% of students aged 16 to 19 years received 3 vaccine doses with 21 median days since the third dose. Protection from previous infection alone was 35.9% (95% confidence interval [CI]: 12.9%-52.8%) and 23.8% (95% CI: 2.1%-40.7%) for students aged 12 to 15 and 16 to 19 years, respectively. Protection from 2-dose hybrid immunity (previous SARS-CoV-2 infection and vaccination) with <180 days since the second dose was 58.7% (95% CI: 33.2%-74.4%) for students aged 12 to 15 and 54.7% (95% CI: 31.0%-70.3%) for students aged 16 to 19 years. Protection was highest (70.0%, 95% CI: 42.3%-84.5%) among students with 3-dose hybrid immunity, although confidence intervals overlap with 2-dose vaccination. CONCLUSIONS The estimated protection against infection was strongest for those with hybrid immunity from previous infection and recent vaccination with a third dose.

中文翻译：

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初中生和高中生中 COVID-19 疫苗接种的既往感染情况和有效性。

背景和目标 了解严重急性呼吸综合征冠状病毒 2 (SARS-CoV-2) 缓解措施（特别是疫苗接种）对聚集环境中的儿童和青少年的现实影响仍然很重要。我们使用基于学校的测试数据评估了对 SARS-CoV-2 感染的保护作用。方法 使用 2022 年 1 月在 omicron (BA.1) 变异占优势期间参加全校抗原测试的犹他州中学生和高中生的数据，对数二项式模型适合估计先前 SARS-CoV-2 感染的保护作用和2019 年冠状病毒病针对 SARS-CoV-2 感染的疫苗接种。结果 在 17 910 名学生中，中位年龄为 16 岁（范围：12-19 岁），16.7% 的学生曾感染过 SARS-CoV-2；55.6% 的人接种了 2 剂疫苗，自第二剂疫苗接种后的中位天数为 211 天；8.6% 的 16 至 19 岁学生接种了 3 剂疫苗，距离第三剂疫苗接种后的中位天数为 21 天。对于 12 至 15 岁和 16 至 19 岁的学生，仅针对既往感染的保护率分别为 35.9%（95% 置信区间 [CI]：12.9%-52.8%）和 23.8%（95% CI：2.1%-40.7%） 。对于 12 至 15 岁的学生，自第二剂接种后 180 天以内的两剂混合免疫（既往 SARS-CoV-2 感染和疫苗接种）保护率为 58.7%（95% CI：33.2%-74.4%），而 12 岁至 15 岁学生为 54.7%（ 16 至 19 岁学生的 95% CI：31.0%-70.3%）。尽管置信区间与 2 剂疫苗接种重叠，但接受 3 剂混合免疫的学生的保护率最高（70.0%，95% CI：42.3%-84.5%）。结论 对于那些对既往感染和最近接种第三剂疫苗具有混合免疫力的人来说，估计的感染保护作用最强。