Ladhani Shamez N, Chow J Yimmy, Janarthanan Roshni, Fok Jonathan, Crawley-Boevey Emma, Vusirikala Amoolya, Fernandez Elena, Perez Marina Sanchez, Tang Suzanne, Dun-Campbell Kate, Evans Edward Wynne-, Bell Anita, Patel Bharat, Amin-Chowdhury Zahin, Aiano Felicity, Paranthaman Karthik, Ma Thomas, Saavedra-Campos Maria, Myers Richard, Ellis Joanna, Lackenby Angie, Gopal Robin, Patel Monika, Brown Colin, Chand Meera, Brown Kevin, Ramsay Mary E, Hopkins Susan, Shetty Nandini, Zambon Maria
Immunisation and Countermeasures Division, Public Health England, 61 Colindale Avenue, London NW9 5EQ, United Kingdom.
Paediatric Infectious Diseases Research Group, St. George's University of London, UK.
EClinicalMedicine. 2020 Sep;26:100533. doi: 10.1016/j.eclinm.2020.100533. Epub 2020 Sep 9.
Care homes are experiencing large outbreaks of COVID-19 associated with high case-fatality rates. We conducted detailed investigations in six London care homes reporting suspected COVID-19 outbreaks during April 2020.
Residents and staff had nasal swabs for SARS CoV-2 testing using RT-PCR and were followed-up for 14 days. They were categorized as symptomatic, post-symptomatic or pre-symptomatic if they had symptoms at the time of testing, in the two weeks before or two weeks after testing, respectively, or asymptomatic throughout. Virus isolation and whole genome sequencing (WGS) was also performed.
Across the six care homes, 105/264 (39.8%) residents were SARS CoV-2 positive, including 28 (26.7%) symptomatic, 10 (9.5%) post-symptomatic, 21 (20.0%) pre-symptomatic and 46 (43.8%) who remained asymptomatic. Case-fatality at 14-day follow-up was highest among symptomatic SARS-CoV-2 positive residents (10/28, 35.7%) compared to asymptomatic (2/46, 4.3%), post-symptomatic (2/10, 20.0%) or pre-symptomatic (3/21,14.3%) residents. Among staff, 53/254 (20.9%) were SARS-CoV-2 positive and 26/53 (49.1%) remained asymptomatic. RT-PCR cycle-thresholds and live-virus recovery were similar between symptomatic/asymptomatic residents/staff. Higher RT-PCR cycle threshold values (lower virus load) samples were associated with exponentially decreasing ability to recover infectious virus (<0.001). WGS identified multiple (up to 9) separate introductions of different SARS-CoV-2 strains into individual care homes.
A high prevalence of SARS-CoV-2 positivity was found in care homes residents and staff, half of whom were asymptomatic and potential reservoirs for on-going transmission. A third of symptomatic SARS-CoV-2 residents died within 14 days. Symptom-based screening alone is not sufficient for outbreak control.
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养老院正经历与高病死率相关的新冠病毒大规模暴发。我们对2020年4月期间报告疑似新冠病毒暴发的伦敦6家养老院进行了详细调查。
居民和工作人员接受鼻拭子检测，采用逆转录聚合酶链反应（RT-PCR）检测新冠病毒，并进行14天的随访。如果他们在检测时、检测前两周或检测后两周出现症状，或全程无症状，则分别被归类为有症状、症状后或症状前，或无症状感染者。同时也进行了病毒分离和全基因组测序（WGS）。
在这6家养老院中，有105/264（39.8%）的居民新冠病毒检测呈阳性，其中有症状的28例（26.7%），症状后的10例（9.5%），症状前的21例（20.0%），无症状的46例（43.8%）。在14天的随访中，有症状的新冠病毒阳性居民的病死率最高（10/28，35.7%），而无症状感染者（2/46，4.3%）、症状后感染者（2/10，20.0%）或症状前感染者（3/21，14.3%）的病死率较低。在工作人员中，53/254（20.9%）的新冠病毒检测呈阳性，其中26/53（49.1%）的人无症状。有症状/无症状居民/工作人员之间的RT-PCR循环阈值和活病毒回收率相似。RT-PCR循环阈值较高（病毒载量较低）的样本，其恢复感染性病毒的能力呈指数下降（<0.001）。全基因组测序确定了多种（多达9种）不同的新冠病毒毒株分别传入各个养老院。
在养老院居民和工作人员中发现新冠病毒阳性的患病率很高，其中一半为无症状感染者，是持续传播的潜在传染源。三分之一有症状的新冠病毒感染者在14天内死亡。仅基于症状的筛查不足以控制疫情暴发。
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