Lessons from the severe acute respiratory syndrome outbreak in Hong Kong

Severe acute respiratory syndrome (SARS) is now a global public health threat with many medical, ethical, social, economic, political, and legal implications. The nonspecific signs and symptoms of this disease, coupled with a relatively long incubation period and the initial absence of a reliable diagnostic test, limited the understanding of the magnitude of the outbreak. This paper outlines our experience with public health issues that have arisen during this outbreak of SARS in Hong Kong. We confirmed that case detection, reporting, clear and timely dissemination of information, and strict infection control measures are essential in handling such an infectious disease outbreak. The need for an outbreak response unit is crucial to combat any future outbreak.     

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.     

Possible meteorological influence on the severe acute respiratory syndrome (SARS) community outbreak at Amoy Gardens, Hong Kong

The largest community outbreak of Severe Acute Respiratory Syndrome (SARS) occurred in the Amoy Gardens residential estate in Hong Kong, in March and April of 2003. It affected more than 300 residents, or 1.7 percent of the total Amoy Gardens population. An airborne pathway has been hypothesized as a possible mode for the spread of the disease. If that hypothesis is correct, meteorological factors may have played a contributory role; the virus-laden aerosols may have been transported between apartment blocks by the ambient wind, low mixing heights may have prevented the efficient dispersion of the aerosols, and a fall in temperature may have fostered the survival of the virus or increased the susceptibility of the exposed population. This information, used in combination with weather forecasts available several days ahead from meteorological services, should be useful for mitigation considerations in the unlikely event of a similar occurrence.     

Understanding the spatial clustering of severe acute respiratory syndrome (SARS) in Hong Kong

We applied cartographic and geostatistical methods in analyzing the patterns of disease spread during the 2003 severe acute respiratory syndrome (SARS) outbreak in Hong Kong using geographic information system (GIS) technology. We analyzed an integrated database that contained clinical and personal details on all 1,755 patients confirmed to have SARS from 15 February to 22 June 2003. Elementary mapping of disease occurrences in space and time simultaneously revealed the geographic extent of spread throughout the territory. Statistical surfaces created by the kernel method confirmed that SARS cases were highly clustered and identified distinct disease "hot spots." Contextual analysis of mean and standard deviation of different density classes indicated that the period from day 1 (18 February) through day 16 (6 March) was the prodrome of the epidemic, whereas days 86 (15 May) to 106 (4 June) marked the declining phase of the outbreak. Origin-and-destination plots showed the directional bias and radius of spread of superspreading events. Integration of GIS technology into routine field epidemiologic surveillance can offer a real-time quantitative method for identifying and tracking the geospatial spread of infectious diseases, as our experience with SARS has demonstrated.     

Predicting super spreading events during the 2003 severe acute respiratory syndrome epidemics in Hong Kong and Singapore

One of the intriguing characteristics of the 2003 severe acute respiratory syndrome (SARS) epidemics was the occurrence of super spreading events (SSEs). Here, the authors report the results of identifying the occurrence of SSEs in the Hong Kong and Singapore epidemics using mathematical and statistical analysis. Their predicted occurrence of SSEs agreed well with the reported occurrence of all seven super spreaders in the two cities. Additional unidentified SSEs were also found to exist. It was found that 71.1% and 74.8% of the infections were attributable to SSEs in Hong Kong and Singapore, respectively. There also seemed to be "synchronized" occurrences of infection peaks in both the community and the hospitals in Hong Kong. The results strongly suggested that the infection did not depend on the total number of symptomatic cases, with only a very small proportion of symptomatic individuals being shown to be infectious (i.e., able to infect other individuals). The authors found that the daily infection rate did not correlate with the daily total number of symptomatic cases but with the daily number of symptomatic cases who were not admitted to a hospital within 4 days of the onset of symptoms.     

Estimating variability in the transmission of severe acute respiratory syndrome to household contacts in Hong Kong, China

The extensive data collection and contact tracing that occurred during the 2003 outbreak of severe acute respiratory syndrome (SARS) in Hong Kong, China, allowed the authors to examine how the probability of transmission varied from the date of symptom onset to the date of hospitalization for household contacts of SARS patients. Using a discrete-time likelihood model, the authors estimated the transmission probability per contact for each day following the onset of symptoms. The results suggested that there may be two peaks in the probability of SARS transmission, the first occurring around day 2 after symptom onset and the second occurring approximately 10 days after symptom onset. Index patients who were aged 60 years or older or whose lactate dehydrogenase level was elevated upon admission to the hospital (indicating higher viral loads) were more likely to transmit SARS to their contacts. There was little variation in the daily transmission probabilities before versus after the introduction of public health interventions on or around March 26, 2003. This study suggests that the probability of transmission of SARS is dependent upon characteristics of the index patients and does not simply reflect temporal variability in the viral load of SARS cases.     

Monitoring the severe acute respiratory syndrome epidemic and assessing effectiveness of interventions in Hong Kong Special Administrative Region

OBJECTIVE: To estimate the infection curve of severe acute respiratory syndrome (SARS) using the back projection method and to assess the effectiveness of interventions. DESIGN: Statistical method. DATA: The daily reported number of SARS and interventions taken by Hong Kong Special Administrative Region (HKSAR) up to 24 June 2003 are used. METHOD: To use a back projection technique to construct the infection curve of SARS in Hong Kong. The estimated epidemic curve is studied to identify the major events and to assess the effectiveness of interventions over the course of the epidemic. RESULTS: The SARS infection curve in Hong Kong is constructed for the period 1 March 2003 to 24 June 2003. Some interventions seem to be effective while others apparently have little or no effect. The infections among the medical and health workers are high. CONCLUSIONS: Quarantine of the close contacts of confirmed and suspected SARS cases seems to be the most effective intervention against spread of SARS in the community. Thorough disinfection of the infected area against environmental hazards is helpful. Infections within hospitals can be reduced by better isolation measures and protective equipments.     

Severe acute respiratory syndrome: a challenge for public health practice in Hong Kong

Severe acute respiratory syndrome (SARS) is now a global challenge affecting more than 8000 patients in different continents. The dictum of public health practice especially for infectious disease is "prevention better than cure". It is especially true for SARS as the treatment strategies remain diverse and experimental. Maintaining a healthy and hygienic environment can be one of the effective public health measures to combat infectious disease. The major challenge is that some of the most important public health measures are to be taken outside the health sector. The community also needs to be strengthened and equipped with the health skills to promote better health and hygiene. There is also the need to create a supportive environment conducive to health for long term sustainability. The WHO approach of promoting health through setting approach would be one possible solution to face the challenge. This paper will describe some of the public health initiatives in Hong Kong through "setting approach" and "community development model" in helping the society fight against SARS. With the emergence of SARS, this might be the time to globalise public health medicine as an important component of medical practice.     

The impact of work-related risk on nurses during the SARS outbreak in Hong Kong

Severe acute respiratory syndrome (SARS) is a highly infectious disease, with high potential for transmission to close contacts, particularly among healthcare workers. This is the first systematic study investigating hospital nurses' physical and psychological health status and the kinds of healthcare used-stratified by the level of contact with SARS patients-during the 2003 outbreak in Hong Kong. Nurses in moderate-risk areas appeared to have more stress symptoms than those working in high-risk areas. It is essential to design hospital support systems and occupational health policy to promote the psychological well-being of nurses during future outbreaks of emerging infections.     

Duration of antibody responses after severe acute respiratory syndrome

Among 176 patients who had had severe acute respiratory syndrome (SARS), SARS-specific antibodies were maintained for an average of 2 years, and significant reduction of immunoglobulin G-positive percentage and titers occurred in the third year. Thus, SARS patients might be susceptible to reinfection >or=3 years after initial exposure.     

Factors influencing the wearing of facemasks to prevent the severe acute respiratory syndrome among adult Chinese in Hong Kong

BACKGROUND: The global outbreak of the severe acute respiratory syndrome (SARS) in 2003 has been an international public health threat. Quick diagnostic tests and specific treatments for SARS are not yet available; thus, prevention is of paramount importance to contain its global spread. This study aimed to determine factors associating with individuals' practice of the target SARS preventive behavior (facemask wearing). METHODS: A total of 1329 adult Chinese residing in Hong Kong were surveyed. The survey instrument included demographic data, measures on the five components of the Health Belief Model, and the practice of the target SARS preventive behavior. Logistic regression analyses were conducted to determine rates and predictors of facemask wearing. RESULTS: Overall, 61.2% of the respondents reported consistent use of facemasks to prevent SARS. Women, the 50-59 age group, and married respondents were more likely to wear facemasks. Three of the five components of the Health Belief Model, namely, perceived susceptibility, cues to action, and perceived benefits, were significant predictors of facemask-wearing even after considering effects of demographic characteristics. CONCLUSIONS: The Health Belief Model is useful in identifying determinants of facemask wearing. Findings have significant implications in enhancing the effectiveness of SARS prevention programs.     

The epidemiology of the outbreak of severe acute respiratory syndrome (SARS) in Hong Kong--what we do know and what we don't

Severe acute respiratory syndrome (SARS) struck Hong Kong bitterly in the spring of 2003, infecting 1755 persons and claiming nearly 300 lives. The epidemic was introduced by travellers from southern China, where the disease had originated. It started in late February and lasted until early June. Two notable 'super-spreading' events were reported, one inside a teaching hospital and the other in a private housing estate. Other than in the super-spreading events, the infectivity in the community appeared to be low, and there were few, if any, asymptomatic or subclinical infections. Health-care workers were at particular risk and accounted for 22 % of all probable cases. The main modes of transmission were through droplet spread and close/direct contacts, but situations conducive to aerosol generation appeared to be associated with higher risk. Our review suggests that there are still many unknown factors concerning the mode of transmission and environmental risk that need to be clarified.     

Exploratory study on psychosocial impact of the severe acute respiratory syndrome (SARS) outbreak on Chinese students living in Japan

The aim of this study is to explore the impact of the 2003 SARS outbreak on Chinese students living in Japan. A cross-sectional study was conducted using a semi-structured questionnaire. The participants were recruited at multiple locations at the University of Tokyo, Japan. The results showed approximately 60% (96/161) of the respondents felt an impact of SARS on college life; they had experienced SARS-related fear, worry, depression as well as social discrimination and had taken SARS prevention measures for daily protection in Japan during the epidemic. The magnitude of the impact was associated with socio-demographic factors, including their age, specialty, area of previous residence in China and length of stay in Japan. The findings suggest that the SARS outbreak had a psychosocial impact on the Chinese students living in Japan, even though none of them had SARS. Social support tailored for these foreign students should be provided during such a disease outbreak.     

Hindsight: a re-analysis of the severe acute respiratory syndrome outbreak in Beijing

OBJECTIVE: To review the severe acute respiratory syndrome (SARS) epidemic in Beijing using basic epidemiological principles omitted from the original analysis. STUDY DESIGN: Analysis of Prospective surveillance data for Beijing collected during the outbreak. METHODS: Surveillance data were reclassified according to World Health Organization criteria. Cases previously excluded without date of onset of illness were included in the epidemic curve from estimates using the average time between date of onset and date of hospitalization for cases with both dates. Cases who failed to give a contact history were now included; 7% (n=5) of cases during the import phase and 61% (n=365) during the peak phase. Previously excluded cases were included for plotting on an epidemic curve, and basic spot mapping for distribution of cases was used from attack rates recalculated for age, gender, occupation, residential location, date of onset of illness and demographics. RESULTS: The spot map effectively illustrated clusters by residency, with the inner-city sustaining the highest attack rate (33.42 per 100,000), followed by an easterly distribution 5-30km away (21.62 per 10,000), and lowest in districts 60-160km away (9.21 per 100,000). The new epidemic curve shows the outbreak commencing 10 days earlier than initially reported, with a three-fold greater increase in cases during the escalation phase than previously estimated. CONCLUSION: In hindsight, the investigation of the Beijing SARS would have benefited from the use of spot maping as an essential outbreak tool for early identification of specific geographical area(s) for quarantining. If a spot map of incidence density rates was used during the early phase of the outbreak, the inner city might have been identified as a major risk factor requiring rapid quarantining. Contact history became uncommon as the outbreak progressed, suggesting that hospitals were over-burdened or pathogenesis and environment risk factors changed, strengthening the usefulness of early spot mapping and the need to modify risk factors included as contact history as the epidemic progresses.     

突发性感染事件及其控制要点--广东省传染性非典型肺炎预防与控制

突发性感染事件通常是指某种已知的或未知的感染性疾病在某一时间段“突然”集中发生于较多病人的疫情。已知传染病的突然暴发,以20世纪70年代末的登革热最具代表性,它在中国销声匿迹30     

SARS信息质量监控方案与实施

针对小汤山医院在SARS诊疗过程中信息质量出现的缺陷,提出具体实施方案:实时信息监控实施方案和终末信息监控实施方案,以便尽可能快地发现可疑数据,发出预警提示,反馈给有关用户,以保证信息质量的完整、详实.     

我市医务人员严重急性呼吸综合征医院感染流行原因调查与对策

目的 调查某市医务人员感染严重急性呼吸综合征(severe acute respiratory syndrome，SARS)的途径及危险因素。方法 对直接参加过抢救和间接接触SARS患而被感染的医务人员采取统一填表、座谈、走访、电话采访等方式进行调查。结果 调查三所医院感染SARS的医务人员共88人，占全市发病医务人员总人数的87．13％。导致医务人员易感的原因是：对疾病缺乏认识，防范意识不强；管理网络不健全；患隐瞒流行病史；隔离环境及防护用品达不到要求等。结论 重视医院感染管理及对医务人员的医院感染知识培训，强化消毒隔离和自我保护意识，是控制医院感染流行及保护医务人员的有力措施。     

Hospital waste generation during an outbreak of severe acute respiratory syndrome in Taiwan.

During the SARS outbreak in Taiwan, the number of ambulatory patients and inpatients treated at one medical center decreased by 40%-70% because of the increasing number of SARS patients. At the peak of the epidemic, the amount of hospital infectious waste had increased from a norm of 0.85 kg per patient-day to 2.7 kg per patient-day. However, the hospital was able to return the generation of waste to normal levels within 10 days.