Assessment of SARS-CoV-2 Infection Prevalence in Homeless Shelters — Four U.S. Cities, March 27–April 15, 2020
Early Release / April 22, 2020 / 69

https://www.cdc.gov/mmwr/volumes/69/wr/mm6917e1.htm?s_cid=mm6917e1_w

In the United States, approximately 1.4 million persons access emergency shelter or transitional housing each year (1). These settings can pose risks for communicable disease spread. In late March and early April 2020, public health teams responded to clusters (two or more cases in the preceding 2 weeks) of coronavirus disease 2019 (COVID-19) in residents and staff members from five homeless shelters in Boston, Massachusetts (one shelter); San Francisco, California (one); and Seattle, Washington (three). The investigations were performed in coordination with academic partners, health care providers, and homeless service providers. Investigations included reverse transcription–polymerase chain reaction testing at commercial and public health laboratories for SARS-CoV-2, the virus that causes COVID-19, over approximately 1–2 weeks for residents and staff members at the five shelters. During the same period, the team in Seattle, Washington, also tested residents and staff members at 12 shelters where a single case in each had been identified. In Atlanta, Georgia, a team proactively tested residents and staff members at two shelters with no known COVID-19 cases in the preceding 2 weeks. In each city, the objective was to test all shelter residents and staff members at each assessed facility, irrespective of symptoms. Persons who tested positive were transported to hospitals or predesignated community isolation areas.

Overall, 1,192 residents and 313 staff members were tested in 19 homeless shelters (Table). When testing followed identification of a cluster, high proportions of residents and staff members had positive test results for SARS-CoV-2 in Seattle (17% of residents; 17% of staff members), Boston (36%; 30%), and San Francisco (66%; 16%). Testing in Seattle shelters where only one previous case had been identified in each shelter found a low prevalence of infection (5% of residents; 1% of staff members). Among shelters in Atlanta where no cases had been reported, a low prevalence of infection was also identified (4% of residents; 2% of staff members). Community incidence in the four cities (the average number of reported cases in the county per 100,000 persons per day during the testing period) varied, with the highest (14.4) in Boston and the lowest (5.7) in San Francisco (2).

The findings in this report are subject to at least three limitations. First, testing represented a single time point. Second, although testing all residents and staff members at each shelter was the objective, some were not available or declined (e.g., in San Francisco 143 of an estimated 255 residents at risk were tested). Finally, symptom information for persons tested was not consistently available and thus not included, although symptom information from Boston is available elsewhere.*

Homelessness poses multiple challenges that can exacerbate and amplify the spread of COVID-19. Homeless shelters are often crowded, making social distancing difficult. Many persons experiencing homelessness are older or have underlying medical conditions (1,3), placing them at higher risk for severe COVID-19–associated illness (4).

To protect homeless shelter residents and staff members, CDC recommends that homeless service providers implement recommended infection control practices, apply social distancing measures including ensuring residents’ heads are at least 6 feet (2 meters) apart while sleeping, and promote use of cloth face coverings among all residents.+ These measures become especially important once ongoing COVID-19 transmission is identified within communities where shelters are located. Given the high proportion of positive tests in the shelters with identified clusters and evidence for presymptomatic and asymptomatic transmission of SARS-CoV-2 (5), testing of all residents and staff members regardless of symptoms at shelters where clusters have been detected should be considered. If testing is easily accessible, regular testing in shelters before identifying clusters should also be considered. Testing all persons can facilitate isolation of those who are infected to minimize ongoing transmission in these settings.


评估无家可归者收容所的SARS-CoV-2感染流行率

在美国，每年约有140万人获得紧急住所或过渡性住房。这些环境可能造成传染病传播的风险。在2020年3月底和4月初，公共卫生团队对来自马萨诸塞州波士顿（1个收容所）、加利福尼亚州旧金山（1个）和华盛顿州西雅图（3个）的5个无家可归者收容所的居民和工作人员中的2019年冠状病毒病（COVID-19）的群集（前2周内有2个或更多的病例）进行了检测。这些调查是在与学术伙伴、卫生保健提供者和无家可归者服务提供者的协调下进行的。调查包括在商业和公共卫生实验室进行反转录聚合酶链式反应检测，对五个庇护所的居民和工作人员进行了大约1-2周的SARS-CoV-2（导致COVID-19的病毒）检测。在同一时期，华盛顿州西雅图的小组还对12个收容所的居民和工作人员进行了检测，每个收容所都发现了一个病例。在佐治亚州亚特兰大，一个小组主动对两个庇护所的居民和工作人员进行了测试，在过去两周内没有发现任何COVID-19病例。在每个城市，目标是对每个被评估设施内的所有收容所居民和工作人员进行检测，无论其症状如何。检测结果呈阳性的人被送往医院或预先指定的社区隔离区。


总的来说，在19个无家可归者收容所中，有1 192名居民和313名工作人员接受了检测。在确定了一个群体之后进行测试时，西雅图、波士顿（36%；30%）和旧金山（66%；16%）的居民和工作人员的SARS-CoV-2检测结果呈阳性的比例较高。在西雅图的庇护所中，每个庇护所只发现了一个以前的病例，而在西雅图庇护所的检测结果显示感染率较低（5%的居民；1%的工作人员）。在亚特兰大没有报告病例的收容所中，也发现了低感染率（4%的居民；2%的工作人员）。4个城市的社区感染率（测试期间，全县每10万人每天平均报告的病例数）各不相同，其中波士顿最高（14.4），旧金山最低（5.7）。

本报告的研究结果至少有三个限制。第一，测试只代表一个时间点。第二，虽然每个庇护所的目标是测试所有的居民和工作人员，但有些人无法提供或拒绝接受测试（例如，在旧金山，估计有255名高危居民中，有143人接受了测试）。最后，受测者的症状信息并不一致，因此没有列入，尽管波士顿的症状信息在其他地方也有。

无家可归者构成了多重挑战，可能会加剧和扩大COVID-19的传播。无家可归者收容所往往拥挤不堪，难以与社会疏远。许多无家可归的人年龄较大或有潜在的疾病(1,3)，使他们有更高的风险，易患COVID-19相关的严重疾病。

为了保护无家可归者收容所的居民和工作人员，疾病预防控制中心建议无家可归者服务提供者实施建议的感染控制措施，采取社会疏导措施，包括确保居民睡觉时头部至少相隔6英尺（2米），并在所有居民中推广使用布质面罩。考虑到在已确定的收容所中，有很高的阳性检测比例，而且有证据表明SARS-CoV-2的无症状和无症状传播(5)，应考虑在已发现有菌群的收容所对所有居民和工作人员进行检测，而不论其症状如何。如果检测很容易获得，也应考虑在庇护所内进行定期检测，然后再确定菌群。对所有人员进行检测，可以促进隔离感染者，以尽量减少在这些环境中的持续传播。
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