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.     

A tale of two cities: community psychobehavioral surveillance and related impact on outbreak control in Hong Kong and Singapore during the severe acute respiratory syndrome epidemic.

OBJECTIVES: To compare the public's knowledge and perception of SARS and the extent to which various precautionary measures were adopted in Hong Kong and Singapore. DESIGN: Cross-sectional telephone survey of 705 Hong Kong and 1,201 Singapore adults selected by random-digit dialing. RESULTS: Hong Kong respondents had significantly higher anxiety than Singapore respondents (State Trait Anxiety Inventory [STAI] score, 2.06 vs 1.77; P < .001). The former group also reported more frequent headaches, difficulty breathing, dizziness, rhinorrhea, and sore throat. More than 90% in both cities were willing to be quarantined if they had close contact with a SARS case, and 70% or more would be compliant for social contacts. Most respondents (86.7% in Hong Kong vs 71.4% in Singapore; P < .001) knew that SARS could be transmitted via respiratory droplets, although fewer (75.8% in Hong Kong vs 62.1% in Singapore; P < .001) knew that fomites were also a possible transmission source. Twenty-three percent of Hong Kong and 11.9% of Singapore respondents believed that they were "very likely" or "somewhat likely" to contract SARS during the current outbreak (P < .001). There were large differences between Hong Kong and Singapore in the adoption of personal precautionary measures. Respondents with higher levels of anxiety, better knowledge about SARS, and greater risk perceptions were more likely to take comprehensive precautionary measures against the infection, as were older, female, and more educated individuals. CONCLUSION: Comparative psychobehavioral surveillance and analysis could yield important insights into generic versus population-specific issues that could be used to inform, design, and evaluate public health infection control policy measures.     

Severe acute respiratory syndrome, Beijing, 2003

The largest outbreak of severe acute respiratory syndrome (SARS) struck Beijing in spring 2003. Multiple importations of SARS to Beijing initiated transmission in several healthcare facilities. Beijing's outbreak began March 5; by late April, daily hospital admissions for SARS exceeded 100 for several days; 2,521 cases of probable SARS occurred. Attack rates were highest in those 20-39 years of age; 1% of cases occurred in children <10 years. The case-fatality rate was highest among patients >65 years (27.7% vs. 4.8% for those 20-64 years, p < 0.001). Healthcare workers accounted for 16% of probable cases. The proportion of case-patients without known contact to a SARS patient increased significantly in May. Implementation of early detection, isolation, contact tracing, quarantine, triage of case-patients to designated SARS hospitals, and community mobilization ended the outbreak.     

The SARS outbreak in a general hospital in Tianjin, China -- the case of super-spreader

Severe acute respiratory syndrome (SARS) is a newly emerged infectious disease with a high case-fatality rate and devastating socio-economic impact. In this report we summarized the results from an epidemiological investigation of a SARS outbreak in a hospital in Tianjin, between April and May 2003. We collected epidemiological and clinical data on 111 suspect and probable cases of SARS associated with the outbreak. Transmission chain and outbreak clusters were investigated. The outbreak was single sourced and had eight clusters. All SARS cases in the hospital were traced to a single patient who directly infected 33 people. The patients ranged from 16 to 82 years of age (mean age 38.5 years); 38.7% were men. The overall case fatality in the SARS outbreak was 11.7% (13/111). The outbreak lasted around 4 weeks after the index case was identified. SARS is a highly contagious condition associated with substantial case fatality; an outbreak can result from one patient in a relatively short period. However, stringent public health measures seemed to be effective in breaking the disease transmission chain.     

The impact of community psychological responses on outbreak control for severe acute respiratory syndrome in Hong Kong

OBJECTIVE: To examine the public's knowledge and perception of SARS and the extent to which various precautionary measures have been adopted. DESIGN: Cross sectional survey. SETTING: General population of Hong Kong at the height of the SARS outbreak (29 March to 6 April 2003). PARTICIPANTS: 1115 ethnic Chinese adults. Main results: Forty per cent did not recognise fomites as a possible mode of transmission whereas 55.1% believed that the infection could be transmitted airborne. A large proportion (30.1%) believed they were very or somewhat likely to contract SARS while only one quarter believed they were very likely to survive if they contracted the disease, benchmarked against an actual case fatality ratio of 2.8% at the time of the survey and 15%-20% according to current best estimates. Precautionary measures directed against person to person droplet spread were generally adopted by most while the prevention of transmission through fomites was not practised as frequently. Respondents with higher risk perceptions and a moderate level of anxiety were most likely to take comprehensive precautionary measures against the infection, as were older, female, more educated people as well as those with a positive contact history and SARS-like symptoms. CONCLUSIONS: The findings demonstrate that the promotion of protective personal health practices to interrupt the self sustaining transmission of the SARS virus in the community must take into account background perceptions of risk and anxiety levels of the public at large. Continuing public education about preventive measures should be targeted at the identified groups with low current uptake of precautions.     

Community Under Stress: Trust,Reciprocity, and Community Collective Efficacy During SARS Outbreak

The study of epidemics is almost non-existent in sociological literature, even though such outbreaks can have detrimental effects on communities. The occurrence of SARS (Severe Acute Respiratory Syndrome) in 2003 provides a rare opportunity to understand the social functioning of a community during the outbreak of an epidemic. To evaluate the extensive social impact of such an outbreak, we focus on the effects of perceived collective efficacy. Specifically, we focus on how the collective efficacy of a community, measured by trust and reciprocal relations, is related to collective action in places where SARS occurred and those where SARS did not occur. The study is based on a unique data set, the 2003 Taiwan Social Image Survey, collected during the outbreak of SARS in Taiwan. Our findings show that community collective efficacy, measured by trust and reciprocity, is not associated with community collective action when an outbreak of an epidemic occurs.     

SARS流行期间公众心理状况调查

目的 探讨SARS流行期间公众心理健康状况，为心理干预提供依据。方法采用SCL-90量表，对2844名学生及城市社区居民和农村居民进行SARS流行期间的心理健康状况问卷调查。结果（1）SARS流行期间公众心理健康状况较全国常模差。（2）不同类群公众在SARS流行期间心态变化不尽相同，产生的心理卫生问题也不同。结论（1）SARS流行期间公众的心理危机问题值得关注。（2）SARS及其它公共卫生事件发生期间的心理危机干预非常必要，但要有针对性。     

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.     

Management of inpatients exposed to an outbreak of severe acute respiratory syndrome (SARS)

This is a prospective observational study of a cohort of inpatients exposed to a severe acute respiratory syndrome (SARS) outbreak. Strict infection control policies were instituted. The 70 patients exposed to the SARS outbreak were isolated from the rest of the hospital. They were triaged, quarantined and cohorted in three open plan wards. Selective isolation was carried out immediately when symptoms and signs suspicious of SARS manifested clinically. The patients' ages ranged from 21 to 90 years and 56% had surgery before the quarantine. Sixteen patients with unexplained fever during the period of quarantine were isolated, seven of whom were eventually diagnosed with probable SARS. The crude incidence of SARS in our cohort was 10%. The SARS case fatality was 14%. No secondary transmission of the SARS virus within the cohort was observed. Strict infection control, together with appropriate triaging, cohorting and selective isolation, is an effective and practical model of intervention in cohorts exposed to a SARS outbreak. Such a management strategy eases the logistic constraints imposed by demands for large numbers of isolation facilities in the face of a massive outbreak.     

Late recognition of SARS in nosocomial outbreak, Toronto

Late recognition of severe acute respiratory syndrome (SARS) was associated with no known SARS contact, hospitalization before the nosocomial outbreak was recognized, symptom onset while hospitalized, wards with SARS clusters, and postoperative status. SARS is difficult to recognize in hospitalized patients with a variety of underlying conditions in the absence of epidemiologic links.     

四川省首起家庭内暴发传染性非典型肺炎调查

目的 对四川省首起可疑传染性非典型肺炎(SARS)的家庭暴发病例进行流行病学调查，病原学、血清学检测，明确诊断。方法 对发生于2003年2月12日的首起家庭暴发病例进行流行病学调查，病原学和血清学检测。结果该起暴发发生于四川省广元市某厂，1家3口皆发病，有密切接触史，符合传染性非典型肺炎的临床诊断标准。患者鼻和咽拭子，上呼吸道分泌物标本，均未分离到流感病毒，禽流感病毒和肺炎衣原体。患者A恢复期血冠状病毒IgM和IgG抗体阳性，患者B恢复期血冠状病毒IgG抗体阳性，患者C急性期血冠状病毒和肺炎衣原体IgM抗体阳性。结论 该起暴发的流行病学、临床特征、血清学等均符合传染性非典型肺炎的诊断。为四川省首起传染性非典型肺炎疫情。     

Crisis prevention and management during SARS outbreak, Singapore

We discuss crisis prevention and management during the first 3 months of the severe acute respiratory syndrome (SARS) outbreak in Singapore. Four public health issues were considered: prevention measures, self-health evaluation, SARS knowledge, and appraisal of crisis management. We conducted telephone interviews with a representative sample of 1,201 adults, > or = 21 years of age. We found that sex, age, and attitude (anxiety and perception of open communication with authorities) were associated with practicing preventive measures. Analysis of Singapore's outbreak improves our understanding of the social dimensions of infectious disease outbreaks.     

SARS流行前后医务人员锻炼、休息及心理状况的调查分析

目的　调查严重急性呼吸道综合症 (SARS)流行前后医务人员锻炼时间、休息时间和心理状况 ,为今后防治SARS或类似传染性疾病提供借鉴。　方法　采用现场填写调查表法。　结果　SARS流行时 ,医务人员睡眠时间、体育锻炼时间均显著少于流行前或流行后 (P均 <0 .0 1) ;心理紧张人数显著多于流行前或流行后 (P均 <0 .0 1)。　结论　SARS流行时 ,医务人员锻炼和休息需要督促和指导 ,他们的心理状态亦需要被了解和调整     

Psychological impact of the 2003 severe acute respiratory syndrome outbreak on health care workers in a medium size regional general hospital in Singapore

AIMS: To describe the psychological impact of severe acute respiratory syndrome (SARS) on health care workers in a regional general hospital 2 months post-outbreak. METHOD: Doctors and nurses were encouraged to participate. The survey consisted of self-report measures: demographics, the General Health Questionnaire (GHQ) 28 and Impact of Events Scale (IES). A questionnaire enquiring about changes in life's priorities due to SARS and circumstances that helped with coping was used. Participation was strictly voluntary and responses anonymous. RESULTS: In total 177 out of 661 (27%) participants [40 out of 113 (35%) doctors and 137 out of 544 (25%) nurses] had a GHQ 28 score >or=5. Doctors [P = 0.026, odds ratio (OR) = 1.6 and 95% confidence interval (CI) = 1.1-2.5] and single health care workers were at higher risk (P = 0.048, OR = 1.4 and 95% CI = 1.02-2.0) compared to nurses and those who were married. Approximately 20% of the participants had IES scores >or=30, indicating the presence of post-traumatic stress disorder (PTSD). Four areas were classified as more important using factor analysis: health and relationship with the family, relationship with friends/colleagues, work and spiritual. The areas for coping strategies were clear directives/precautionary measures, ability to give feedback to/obtain support from management, support from supervisors/colleagues, support from the family, ability to talk to someone and religious convictions. Support from supervisors/colleagues was a significant negative predictor for psychiatric symptoms and PTSD. Work and clear communication of directives/precautionary measures also helped reduce psychiatric symptoms. CONCLUSIONS: Many health care workers were emotionally affected and traumatized during the SARS outbreak. Hence, it is important for health care institutions to provide psychosocial support and intervention for their health care workers.     

SARS-CoV毒株E、M、N和S基因分子变异研究

目的通过对SARS-CoV毒株基因序列的变异分析,揭示SARS-CoV毒株出现和流行与基因进化的关系.方法对广东地区SARS-CoV毒株进行序列分析,其余毒株序列从GenBank检索,采用DNAstar 5.0软件,对检索的SARS-CoV的E、M、N、S基因核苷酸序列进行比对和分析;并结合临床资料对变异毒株进行流行病学分析.结果以果子狸冠状病毒(SZ-3)为基准,102株人类毒株中,6株毒株E基因的4个氨基酸发生置换,两株毒株发生缺失变异;果子狸毒株M基因的第5位丝氨酸置换为人类毒株甘氨酸并减少1个糖蛋白位点,此外M基因有38株毒株发生8个氨基酸置换变异;6株毒株N基因发生氨基酸置换,3株毒株发生缺失变异;人类毒株S基因中9个氨基酸全部发生变异并增加1个糖蛋白位点,与果子狸毒株不同比例占0.72%(9/1255);部分毒株中S基因的27个氨基酸在发生置换变异,7株毒株发生缺失变异.结论冠状病毒S基因中9个氨基酸置换和1个糖蛋白位点影响,可能导致人类SARS-CoV毒株出现和SARS流行;SARS流行持续和传播扩大与S基因进化变异相一致.所以认为,SARS-CoV毒株S基因变异可能在SARS出现和流行中发挥极其重要的作用.     

How often do you wash your hands? A review of studies of hand-washing practices in the community during and after the SARS outbreak in 2003

We reviewed evidence of hand-washing compliance in community settings during the 2003 SARS outbreak. Literature was searched through PubMed, Cochrane Library, Wan Fang database and Google. English and Chinese papers were reviewed. Studies containing data on hand-washing, self-reported or directly observed, in community settings were selected. Case-control studies and studies in healthcare settings were excluded. Fourteen studies were reviewed. Self-reported hand-washing compliance increased in the first phase of the SARS outbreak and maintained a high level 22 months after the outbreak. The decline of hand-washing in Hong Kong after SARS was relatively slow. A significant gender difference in hand-washing compliance (female > male) was found in eight studies. The importance of family support and 'significant female others' in hand hygiene promotion are noted. The impact of education is uncertain. Perceived susceptibility to and severity of SARS, and perceived efficacy of hand-washing in preventing SARS, also predicted self-reported hand-washing compliance.     

"Exposing the cracks": Severe Acute Respiratory Syndrome and the Hong Kong health system

PURPOSE: Hong Kong was particularly affected by the 2003 outbreak of Severe Acute Respiratory Syndrome (SARS). During the epidemic, it seemed as if the Hong Kong government and health system were barely coping, leading to calls of mismanagement and governance incapacity. In the wake of the SARS outbreak, two inquiries were conducted. The purpose of this article is to review the Hong Kong's response to SARS from the perspective of two inquiries. DESIGN/METHODOLOGY/APPROACH: An historical analysis of the institutional arrangements for health care delivery in Hong Kong is undertaken, followed by a chronology of developments in the SARS outbreak. The article then reviews outbreak management and the findings of the two inquiries. Finally, it considers whether the Hong Kong health system can be reformed to manage any future infectious disease epidemic better. FINDINGS: Both leadership and coherency were lacking in Hong Kong's response to SARS. These are age-old problems in the Hong Kong health sector. The prospects for mending the health system appear limited, given that leadership and coherency have been consistently absent features of post-1997 governance in Hong Kong. RESEARCH LIMITATIONS/IMPLICATIONS: This article reviews events in the immediate period following the SARS outbreak. A future follow-up study of the Hong Kong government and health system's capacity to respond to infectious disease outbreaks would be useful. PRACTICAL IMPLICATIONS: This article provides a review that will be useful to policymakers and researchers. ORIGINALITY/VALUE: No other article reviews the Hong Kong health system's SARS response.     

The Singaporean response to the SARS outbreak: knowledge sufficiency versus public trust

During the outbreak of severe acute respiratory syndrome (SARS) in Singapore from 1 March to 11 May 2003, various national prevention and control measures were undertaken to control and eliminate the transmission of the infection. During the initial period of the epidemic, public communication was effected through press releases and media coverage of the epidemic. About a month into the epidemic, a public education campaign was mounted to educate Singaporeans on SARS and adoption of appropriate behaviours to prevent the spread of the disease. A survey was conducted in late April 2003 to assess Singaporeans' knowledge about SARS and infection control measures, and their concerns and anxiety in relation to the outbreak. The survey also sought to assess their confidence in the ability of various institutions to deal with SARS and their opinion on the seemingly tough measures enforced. The study involved 853 adults selected from a telephone-sampling frame. Stratified sampling was used to ensure adequate representation from major ethnic groups and age groups. The study showed that the overall knowledge about SARS and control measures undertaken was low (mean per cent score of 24.5 +/- 8.9%). While 82% of respondents expressed confidence in measures undertaken by Tan Tock Seng Hospital (the hospital designated to manage SARS), only 36% had confidence in nursing homes. However, >80% of the public agreed that the preventive and control measures instituted were appropriate. Despite the low knowledge score, the overall mean satisfaction score of the government's response to SARS was 4.47 (out of possible highest score of 5.00), with >93% of adult Singaporeans indicating that they were satisfied or very satisfied with the government's response to SARS. Generally, Singaporeans had a high level of public trust (satisfaction with government, confidence in institutions, deeming government measures appropriate), scoring 11.4 out of possible maximum of 14. The disparity between low knowledge on the one hand and high confidence and trust in the actions of the government on the other suggests that Singaporeans do not require high knowledge sufficiency to be confident in measures undertaken by the government to control the SARS crisis.     

定量评价SARS干预措施效果的传播动力学模型

目的建立一种可以用于严重急性呼吸综合征(SARS)干预措施效果定量评价的传播动力学模型。方法根据SARS流行规律,以传染病SEIR流行模型为基础,增设病例管理人群和控制措施相关参数,从而建立起SARS的传播动力学模型。以北京市2003年SARS流行为实例,说明所建模型在干预措施效果定量评价上的应用。结果所建立的模型可以随时调整干预措施相关参数。通过干预情景假定,可以模拟各种干预措施情况下SARS的流行过程,从而对干预措施效果做出定量评价。实例研究发现,该模型可以较好地模拟北京市2003年SARS流行过程;北京市2003年4月20日前后采取的措施对SARS疫情控制起到了关键性的作用。结论所建立的SARS流行模型是可靠和稳定的,可以用于SARS干预措施效果的定量评价。     

Managing febrile respiratory illnesses during a hypothetical SARS outbreak

Since the World Health Organization declared the global outbreak of severe acute respiratory syndrome (SARS) contained in July 2003, new cases have periodically reemerged in Asia. This situation has placed hospitals and health officials worldwide on heightened alert. In a future outbreak, rapidly and accurately distinguishing SARS from other common febrile respiratory illnesses (FRIs) could be difficult. We constructed a decision-analysis model to identify the most efficient strategies for managing undifferentiated FRIs within a hypothetical SARS outbreak in New York City during the season of respiratory infections. If establishing reliable epidemiologic links were not possible, societal costs would exceed 2.0 billion US dollars per month. SARS testing with existing polymerase chain reaction assays would have harmful public health and economic consequences if SARS made up <0.1% of circulating FRIs. Increasing influenza vaccination rates among the general population before the onset of respiratory season would save both money and lives.