Efficiency of quarantine during an epidemic of severe acute respiratory syndrome--Beijing, China, 2003

During March--July 2003, an epidemic of severe acute respiratory syndrome (SARS) in Beijing, China, accounted for 2,521 probable cases (attack rate: 19 per 100,000 population). To control the epidemic, public health officials initiated enhanced surveillance, isolation of SARS patients, use of personal protective equipment (PPE) by health-care workers, and quarantine of contacts of known SARS patients. Approximately 30,000 Beijing residents were quarantined in their homes or quarantine sites. To guide future quarantine policy, the Chinese Field Epidemiology Training Program (China FETP) of the Chinese Center for Disease Control and Prevention (China CDC) conducted a survey to estimate the risk for acquiring SARS among quarantined residents of Haidian District (2001 population: 2.24 million), Beijing, in May 2003, 1 month after the epidemic peaked. This report summarizes the results of that survey, which indicate that, as a component of a comprehensive SARS-control program, quarantine should be limited to persons who have contact with an actively ill SARS patient in the home or hospital, allowing for better focus of resources in future outbreaks.     

SARS病区医院感染控制与管理

目的 探讨和总结SARS流行期间，医院感染控制与管理的方法和经验。方法 建立规范隔离病区、制定严格消毒隔离制度和规范消毒方法、采取严格患者管理、有效切断传播途径、加强医护人员防护等综合控制医院感染措施。结果 避免了SARS在医院内的传播，有效预防了医护人员与患者间的交叉感染。结论 加强医院感染控制与管理，针对SARS传播特点，制定科学的消毒隔离制度及医护人员防护措施，对控制SARS医院感染具有重要的作用。     

Seroprevalence of SARS coronavirus antibody in household contacts

Between March and July 2003, 671 cases of severe acute respiratory syndrome (SARS) were diagnosed in Taiwan with a total of 84 fatalities. After the epidemic, a serological survey was conducted involving the asymptomatic household contacts. Household contacts of 13 index patients were enrolled in the study. Contact history and clinical symptoms of the household contacts were recorded by standardized questionnaires. Blood samples of patients and household contacts were collected at least 28 days after symptom onset in the index patients or household exposure in the contacts for SARS-associated coronavirus (SARS-CoV) IgG testing. On the basis of this investigation, 29 persons (25 adults and 4 children) were identified as having had unprotected exposure to the index cases before infection-control practices were implemented. Laboratory evaluation of clinical specimens showed no evidence of transmission of SARS-CoV infection to any contacts. This investigation demonstrated that subclinical transmission among household contacts was low in the described setting.     

天津市传染性非典型肺炎流行特点及主要控制措施效果评价

目的：分析天津市传染性非典型肺炎[严重急性呼吸综合征(SARS)]流行病学特征，对主要控制措施的效果进行初步评价。方法：采用自行设计的病例报告表，全市统一的流行病学个案调查表及病例接触者、密切接触者树状分布图，深入病房、家庭、社区、团体等对病例及接触者进行调查。结果：以发病时间计算，自2003年4月13日至5月8日，包括输入病例在内发病175例，发病率为1．9／10万，其中死亡14例，病死率达8．O％。整个流行过程不足1个月，流行特点：1例“超级传播者”直接或间接传染了全市94．3％的病例；呈现以A、B、C 3家医院聚集发病为特点的爆发性流行，占全市病例的68．6％，3家医院外的家庭聚集发病占全市病例的14．3％，同事间传播为2．3％，散发者为9．1％，这些散发者未造成接触者感染；早期医务人员发病较多，占总病例数的38．2％，流行全过程参加SARS救治工作的1975名医护人员的总感染率为3．4％；全部流行过程传染源明确，传染链清晰，全市仅3例患者未找到传染源，占病例总数的2％；在10例源头病例中仅“超级传播者”和另一病例传染了其接触者，其他传染源由于及时隔离未造成任何传播。结论：SARS是严重急性呼吸系统传染病，如能及时准确地掌握传染链并进行范围适当、及时有效的封闭及隔离措施，以科学的方法提高全民的警觉度，传染链可能在较短时间内被切断，从而控制传播。     

Phylogenetic analysis and sequence comparisons of structural and non-structural SARS coronavirus proteins in Taiwan.

Taiwan experienced a large number of severe acute respiratory syndrome (SARS) viral infections between March and July 2003; by September of that year, 346 SARS cases were confirmed by RT-PCR or serological tests. In order to better understand evolutionary relationships among SARS coronaviruses (SCoVs) from different international regions, we performed phylogenetic comparisons of full-length genomic and protein sequences from 45 human SCoVs (including 12 from Taiwan) and two civet SCoVs. All the Taiwanese SARS-CoV strains which associated with nosocomial infection formed a monophyletic clade within the late phase of the SARS epidemic. This Taiwanese clade could be further divided into two epidemic waves. Taiwan SCoVs in the first wave clustered with three isolates from the Amoy Gardens housing complex in Hong Kong indicating their possible origin. Of the 45 human SCoVs, one isolate from Guangdong province, China, exhibited an extra 29-nucleotide fragment between Orf 10 and Orf 11--similar to the civet SCoV genome. Nucleotide and protein sequence comparisons suggested that all SCoVs of late epidemic came from human-to-human transmission, while certain SCoVs of early epidemic might have originated in animals.     

应用系统动力学模型对SARS疫情传播及主要防控措施效果的计算机模拟仿真研究

目的　(1)应用系统动力学方法建立数学模型,宏观地模拟严重急性呼吸综合征(SARS)疫情在自然人群和医院内传播的过程,以及患者通过就诊和社区隔离措施移出传播链的过程。(2)通过计算机对该模型的仿真模拟,分析在突发 SARS疫情的情况下,代表主要防控措施的变量对疫情曲线的影响模式和相对强度。(3)重点分析发热监测措施对疫情的影响,根据分析结果对今后SARS防控工作提出政策建议。方法　采用面访、问卷调查、文献检索、个案分析等方式,获取SARS传播的重要参数。应用系统动力学理论及计算机仿真系统建立数学模型,并进行 What if仿真分析。结果　建立了能够反映SARS自然传播、患者就诊及医院内传播、社区隔离措施、发热监测过程的计算机仿真模型,通过宏观模拟SARS患者从发病到被移出传播链的过程得出下列结果:(1)患者从发病到就诊的时间、患者每日平均接触人数、就诊时医院内接触人数等是对 SARS的院内、院外传播过程影响最大的几个变量;(2)隔离强度、接诊医生对 SARS的警惕性、医院通风消毒、医院优化患者流动路线、医生防护强度是影响疫情控制的主要变量;(3)医院入口的体温筛查措施对疫情控制的作用不大。结论　按照目前制定的SARS防治预案,卫生系统能够快速控制突发的SARS疫情。     

Severe acute respiratory syndrome--Taiwan, 2003

On April 22, 2003, the Taiwan Department of Health (DOH) was notified of seven cases of severe acute respiratory syndrome (SARS) among health-care workers (HCWs) at a large municipal hospital in Taipei (hospital A). Subsequent cases at eight hospitals have been associated with exposures at hospital A. Previously, all reported cases had been associated with persons recently returning to Taiwan from SARS-affected regions. This report summarizes epidemiologic findings of the outbreak in Taiwan and describes the impact of health-care--associated transmission of SARS.     

国境口岸传染性非典型肺炎检疫措施的研究

目的促进国境口岸防制传染性非典型肺炎(SARS)检疫措施的完善。方法对我国国境口岸SARS检疫措施进行调查研究,收集国内外防制SARS检疫措施的资料,并进行比较。结果在SARS流行期间,世界上大部分国家针对境内的国际机场、港口等出入境口岸,采取了不同的检疫措施,多数采取的是入境口岸检查和填写登记卡。我国在国境口岸实施对出入境人员现场医学观察、检疫检查和要求填写《出(入)境健康申明卡》的检疫措施,有效地防止了SARS的传入传出,但同时也给出入境人员造成了一些麻烦和精神上的负担,不利于检疫措施的实施。包括：修改《出(入)境健康申明卡》,使其内容更简单、科学、有针对性,字更通俗;改进体温测量及处理的操作规程,设立一套科学的口岸检疫应对危机管理机制,对发热病人带来疫病的可能性进行风险评估,分级后采取相应措施。结论借鉴某些国家防制SARS的经验,通过调整和完善检疫措施,防止SARS的传入和传出。     

SARS outbreak, Taiwan, 2003

We studied the severe acute respiratory syndrome (SARS) outbreak in Taiwan, using the daily case-reporting data from May 5 to June 4 to learn how it had spread so rapidly. Our results indicate that most SARS-infected persons had symptoms and were admitted before their infections were reclassified as probable cases. This finding could indicate efficient admission, slow reclassification process, or both. The high percentage of nosocomial infections in Taiwan suggests that infection from hospitalized patients with suspected, but not yet classified, cases is a major factor in the spread of disease. Delays in reclassification also contributed to the problem. Because accurate diagnostic testing for SARS is currently lacking, intervention measures aimed at more efficient diagnosis, isolation of suspected SARS patients, and reclassification procedures could greatly reduce the number of infections in future outbreaks.     

Infection control for SARS in a tertiary paediatric centre in Hong Kong

Severe acute respiratory syndrome (SARS) is an emerging infectious disease. After the appearance of an index patient in Hong Kong in February 2003, SARS outbreaks occurred rapidly in hospitals and spread to the community. The aim of this retrospective study is to evaluate the effectiveness of a triage policy and risk-stratified infection control measures in preventing nosocomial SARS infection among paediatric healthcare workers (HCWs) at the Prince of Wales Hospital, a general hospital to which children with SARS are referred in Hong Kong. The acute paediatric wards were stratified into three areas: (1) ultra high-risk area, (2) high-risk area and (3) moderate-risk area according to different risk levels of nosocomial SARS transmission. The implementation of different levels of infection control precautions was guided by this risk stratification strategy. Between 13 March and 23 June, 38 patients with probable and suspected SARS, 90 patients with non-SARS pneumonia, and 510 patients without pneumonia were admitted into our unit. All probable SARS cases were isolated in negative-pressure rooms. Twenty-six HCWs worked in the ultra high-risk area caring for SARS patients and 88 HCWs managed non-SARS patients in other ward areas. None of the HCWs developed clinical features suggestive of SARS. In addition, there was no nosocomial spread of SARS-associated coronavirus to other patients or visitors during this period. In conclusion, stringent infection control precautions, appropriate triage and prompt isolation of potential SARS patients may have contributed to a lack of nosocomial spread and HCW acquisition of SARS in our unit.     

Infrared thermography to mass-screen suspected SARS patients with fever

Fever greater than 38 degrees C is a cardinal sign of patients with the severe acute respiratory syndromes (SARS). To reduce the risk of nosocomial cross infections, screening all patients and visitors who visit hospitals and clinics for fever at the entrance of every hospital building has become a standard protocol in Taiwan during the SARS epidemic from mid-April to mid-June 2003. We used a digital infrared thermal imaging (DITI) system (Telesis Spectrum 9000 MB) to conduct mass screening of patients and visitors who entered the hospital to identify those with fever. The DITI system has two components: a sensor head and a PC imaging workstation. The sensor head is an optic-mechanical device which consists of imagining optics for focusing the infrared source information on the infrared detector. The infrared images are further converted into electrical signals, which are then processed for real-time display on the monitor. During the period from April 13 to May 12 2003, 72,327 outpatients and visitors entered Taipei Medical University-Wan Fang Hospital, Taipei, Taiwan. A total of 305 febrile patients (0.42%) was detected by infrared thermography. Among them, three probable SARS patients were identified after thorough studies including contact history, laboratory tests and radiology examinations. The findings suggests that infrared thermography was an effective and reliable tool ideal for mass-screening patients with fever in the initial phase of screening for SARS patients at a busy hospital which sees approximately 3,000 outpatients every weekday during the SARS epidemic.     

Quarantine for SARS, Taiwan

During the 2003 outbreak of severe acute respiratory syndrome (SARS) in Taiwan, >150,000 persons were quarantined, 24 of whom were later found to have laboratory-confirmed SARS-coronavirus (SARS-CoV) infection. Since no evidence exists that SARS-CoV is infective before the onset of symptoms and the quarantined persons were exposed but not symptomatic, we thought the quarantine's effectiveness should be investigated. Using the Taiwan quarantine data, we found that the onset-to-diagnosis time of previously quarantined confirmed case-patients was significantly shortened compared to that for those who had not been quarantined. Thus, quarantine for SARS in Taiwan screened potentially infective persons for swift diagnosis and hospitalization after onset, thereby indirectly reducing infections. Full-scale quarantine measures implemented on April 28 led to a significant improvement in onset-to-diagnosis time of all SARS patients, regardless of previous quarantine status. We discuss the temporal effects of quarantine measures and other interventions on detection and isolation as well as the potential usefulness of quarantine in faster identification of persons with SARS and in improving isolation measures.     

Modelling potential responses to severe acute respiratory syndrome in Japan: the role of initial attack size, precaution, and quarantine

BACKGROUND: There has been an outbreak of the severe acute respiratory syndrome (SARS) worldwide. With the use of detailed epidemiological data from other countries, this article describes the possible reason for the SARS epidemic not appearing in Japan, and simulates the impact of different control strategies that can break the transmission cycle of SARS associated coronavirus. METHOD: Mathematical modelling is used for predicting the epidemiological outcome and simultaneously for evaluating the effect of interventions on SARS. The study estimates the initial attack size that would result in failed invasion. Three different interventions have been incorporated into the public health response policies; precautionary public health measures, isolation of infected people, and quarantine of exposed humans. RESULTS: The maximum number of humans newly infected could be roughly estimated on the basis of the initial attack size, using simple formulas. It is seen that the introduction of only a few cases into certain communities would not lead easily to an epidemic. The possible trajectories of SARS epidemic depend on the levels of public health interventions as quarantine and precautionary public health measures greatly affected the transmissibility of the disease. It is shown that there exist threshold levels of interventions at which the SARS epidemic settles down. CONCLUSION: Initial attack size is one of the determinants of whether SARS can successfully invade the community or not. Two of the most effective policy procedures to prevent new infections would be to apply stringent precautionary measures and to impose quicker and more effective quarantine of the exposed populace.     

综合性医院收治SARS病人的医院感染控制

目的 探讨和总结严重急性呼吸综合征(SARS)流行期间，医院感染控制与管理的方法和经验。方法 建立规范隔离病区，制定严格消毒隔离制度和规范消毒方法，采取严格病人管理，有效切断传播途径，加强医护人员防护等综合控制医院感染措施。结果避免了SARS在医院内的传播，有效预防了医护人员与病人间的交叉感染。结论 加强医院感染控制与管理，针对SARS的传播特点，制定科学的消毒隔离制度及医护人员防护措施，对控制SARS医院感染具有重要的作用。     

广西重点人群传染性非典型肺炎监测研究

目的为了及时发现和监控传染性非典型肺炎病例,防止疫情扩散和蔓延,探讨影响疫情发生和发展的因素.方法采用主动与被动相结合的疾病监测方法,在全区范围内对从外地返乡、来桂人群、非典病人密切接触者、发热病人实施监测.结果自2003年4月15日至2003年7月10日,全区组织1076万日人次参与重点人群监测,共监测排查从外省(市)返乡人员625 646人,其中从广东返乡501 596人,累计发现发热病人7067人,确诊为非典病例6例;监测来桂人群201 158人,其中从广东来51 288人,发现发热病人981人,未查出非典病例;隔离观察非典密切接触者2213人,发现非典2例,发病率达90.4/10万;发热门诊接诊709 843例发热病人,其中有3例确诊为非典病例也系返乡民工.结论通过这次大范围监测,广西自4月中旬以后发生的11例非典病人均能在第一时间(48h内)得以发现和监控,有效防止了疫情扩散和蔓延.监测结果还表明广西尚属输入性地区,未发生流行,受到邻省疫情威胁不很严重;同时显示一些市(县)开展人群监测有一定程度过度反应,付出的代价昂贵,急需建立起更高效经济可行适合常态管理的监测手段.     

Control measures for severe acute respiratory syndrome (SARS) in Taiwan

As of April 14, 2003, Taiwan had had 23 probable cases of severe acute respiratory syndrome (SARS), 19 of which were imported. Taiwan isolated all 23 patients in negative-pressure rooms; extensive personal protective equipment was used for healthcare workers and visitors. For the first 6 weeks of the SARS outbreak, recognized spread was limited to one healthcare worker and three household contacts.     

SARS transmission in Vietnam outside of the health-care setting

To evaluate the risk of transmission of SARS coronavirus outside of the health-care setting, close household and community contacts of laboratory-confirmed SARS cases were identified and followed up for clinical and laboratory evidence of SARS infection. Individual- and household-level risk factors for transmission were investigated. Nine persons with serological evidence of SARS infection were identified amongst 212 close contacts of 45 laboratory-confirmed SARS cases (secondary attack rate 4.2%, 95% CI 1.5-7). In this cohort, the average number of secondary infections caused by a single infectious case was 0.2. Two community contacts with laboratory evidence of SARS coronavirus infection had mild or sub-clinical infection, representing 3% (2/65) of Vietnamese SARS cases. There was no evidence of transmission of infection before symptom onset. Physically caring for a symptomatic laboratory-confirmed SARS case was the only independent risk factor for SARS transmission (OR 5.78, 95% CI 1.23-24.24).     

Update: severe acute respiratory syndrome--Toronto,Canada, 2003

Severe acute respiratory syndrome (SARS) was first recognized in Toronto in a woman who returned from Hong Kong on February 23, 2003 (1). Transmission to other persons resulted subsequently in an outbreak among 257 persons in several Greater Toronto Area (GTA) hospitals. After implementation of provincewide public health measures that included strict infection-control practices, the number of recognized cases of SARS declined substantially, and no cases were detected after April 20. On April 30, the World Health Organization (WHO) lifted a travel advisory issued on April 22 that had recommended limiting travel to Toronto. This report describes a second wave of SARS cases among patients, visitors, and health-care workers (HCWs) that occurred at a Toronto hospital approximately 4 weeks after SARS transmission was thought to have been interrupted. The findings indicate that exposure to hospitalized patients with unrecognized SARS after a provincewide relaxation of strict SARS control measures probably contributed to transmission among HCWs. The investigation underscores the need for monitoring fever and respiratory symptoms in hospitalized patients and visitors, particularly after a decline in the number of reported SARS cases.     

Epidemiologic study and containment of a nosocomial outbreak of severe acute respiratory syndrome in a medical center in Kaohsiung, Taiwan.

OBJECTIVE: We conducted an epidemiologic investigation at the beginning of a nosocomial outbreak of severe acute respiratory syndrome (SARS) to clarify the dynamics of SARS transmission, the magnitude of the SARS outbreak, and the impact of the outbreak on the community. METHODS: We identified all potential cases of nosocomially acquired SARS, linked them to the most likely infection source, and described the hospital containment measures. SETTING: A 2,300-bed medical center in Kaohsiung, Taiwan. RESULTS: A total of 55 cases of SARS were identified, and 227 hospital workers were quarantined. The index patient and neighboring patients were isolated. A chest physician team reviewed medical charts and chest radiographs and monitored the development of SARS in patients staying in the ward. The presence of underlying lung disease and immunocompromise in some patients made the diagnosis of SARS difficult. Some cases of SARS were diagnosed after the patients had died. Medical personnel were infected only if they cared for patients with unrecognized SARS, and caretakers played important roles in transmission of SARS to family members. As the number of cases of nosocomial SARS increased, the hospital closed the affected ward and expedited construction of negative-pressure rooms on other vacated floors for patient cohorting, and the last case in the hospital was identified 1 week later. CONCLUSIONS: Timely recognition of SARS is extremely important. However, given the limitations of SARS testing, possible loss of epidemic links, and the nonspecific clinical presentations in hospitalized patients, it is very important to establish cohorts of persons with low, medium, and high likelihoods of SARS acquisition. Rapid closure of affected wards may minimize the impact on hospital operations. Establishment of hospitals dedicated to appropriate treatment of patients with SARS might minimize the impact of the disease in future epidemics.