MMWR Morb Mortal Wkly Rep. 2021 Dec 31;70(5152):1778-1781. doi: 10.15585/mmwr.mm705152e2.
The COVID-19 pandemic has resulted in school closures and reduction of in-person learning (1). In August 2021, the Lake County Health Department (LCHD) in Illinois introduced a Test to Stay (TTS) strategy, whereby unvaccinated students, teachers, and staff members with certain school-related COVID-19 exposures could remain in school and participate in school-related extracurricular activities. Eligibility to participate in TTS required the following conditions to be met: 1) the exposure occurred while both the person with COVID-19 (index patient) and the close contact were masked; 2) the close contact remained asymptomatic, practiced consistent mask wearing, and maintained physical distancing; and 3) the close contact underwent testing for SARS-CoV-2 (the virus that causes COVID-19) on days 1, 3, 5, and 7 after exposure to the index patient. LCHD permitted kindergarten through grade 12 (K-12) schools in Lake County to implement TTS; 90 schools, representing 31 school districts in Lake County, implemented TTS during August 9-October 29, 2021. During the implementation period, 258 COVID-19 cases were reported. Among 1,035 students and staff members enrolled in TTS, the secondary attack risk (number of close contacts who received a positive SARS-CoV-2 test result within 14 days after exposure to an index patient, divided by total number of close contacts) was 1.5% (16 of 1,035). Among the 16 secondary cases identified, all were in students, and none appeared to transmit SARS-CoV-2 to other school-based contacts. However, nine tertiary cases were identified among household contacts of the 16 secondary cases, and four of the nine were fully vaccinated. Assuming a maximum of 8 missed school days for every 10-day quarantine period, up to 8,152 in-person learning days were saved among TTS participants. Implementation of TTS with other concurrent prevention strategies, including masking and physical distancing, limited further spread of SARS-CoV-2 within K-12 schools and allowed students to safely sustain in-person learning. Although vaccination remains the leading public health recommendation to protect against COVID-19 for those aged ≥5 years, schools might consider TTS as an option for allowing close contacts who are not fully vaccinated to remain in the classroom as an alternative to home quarantine.
新冠疫情导致学校关闭，减少了面授学习的机会。2021 年 8 月，伊利诺伊州莱克县卫生局（LCHD）推出了 Test to Stay（TTS）策略，即未接种疫苗的学生、教师和工作人员在与学校相关的 COVID-19 暴露事件中，如果符合某些条件，可以留在学校并参加与学校相关的课外活动。参加 TTS 的资格需要满足以下条件：1）暴露发生时，新冠病毒感染者（索引病例）和密切接触者都戴了口罩；2）密切接触者保持无症状，持续佩戴口罩并保持身体距离；3）密切接触者在接触索引病例后第 1、3、5 和 7 天接受 SARS-CoV-2（导致 COVID-19 的病毒）检测。LCHD 允许莱克县的幼儿园到 12 年级（K-12）学校实施 TTS；莱克县的 31 个学区中的 90 所学校在 2021 年 8 月 9 日至 10 月 29 日期间实施了 TTS。在实施期间，报告了 258 例 COVID-19 病例。在参加 TTS 的 1035 名学生和工作人员中，二次攻击风险（在接触索引病例后 14 天内接受 SARS-CoV-2 检测呈阳性的密切接触者数量除以密切接触者总数）为 1.5%（16/1035）。在确定的 16 例二次病例中，全部为学生，且似乎没有将 SARS-CoV-2 传播给其他学校接触者。然而，在 16 例二次病例的家庭接触者中，确定了 9 例三级病例，其中 4 例完全接种了疫苗。假设每 10 天隔离期最多缺课 8 天，TTS 参与者节省了多达 8152 天的面授学习时间。通过实施 TTS 以及其他预防策略，包括戴口罩和保持身体距离，限制了 SARS-CoV-2 在 K-12 学校内的进一步传播，并使学生能够安全地维持面授学习。尽管接种疫苗仍然是保护 5 岁以上人群免受 COVID-19 侵害的主要公共卫生建议，但学校可以考虑将 TTS 作为允许未完全接种疫苗的密切接触者留在教室的一种选择，而不是进行家庭隔离。
