The international response to the outbreak of SARS in 2003

The sudden arrival of an internationally spreading outbreak of a newly identified infectious disease in early 2003, severe acute respiratory syndrome (SARS), provided an opportunity for a coordinated international response based on information and evidence obtained in real time through standard and electronic communications. Its containment represents a new way of working internationally, and demonstrates how intense collaboration in virology, clinical medicine and epidemiology can rapidly provide the information necessary to create and implement evidence-based control measures. The SARS outbreak serves as a reminder of the need for a strong national surveillance and response to infectious diseases, evidence-based international travel recommendations, and a global alert and response network to serve as a safety net when national surveillance fails.     

北京2003年SARS疫情的数值模拟

在文[1]的基础上,进一步考虑了每天从外地输入北京的SARS病人数和处于传染期的病人在发病后被收治的概率.利用Gauss-Newton最优化方法对相关参数进行了估计,结果表明,初始病人数为3.5人,医院外第一、二阶段的传染率分别为0.5655(1/天)、0.1425(1/天),医院内第一、二阶段的传染率分别为0.0470(1/天)、0.00(1/天),病人发病后八天内被医院收治,期间每天被医院收治的概率从第一天的0.1632严格递减至第八天的0.0776.累计病人数、累计出院与死亡人数之和的模拟值与实际统计值的相对误差都小于1%.     

Factors influencing compliance with quarantine in Toronto during the 2003 SARS outbreak

The purpose of this study was to cull lessons from Toronto's experiences with large-scale quarantine during the outbreak of Severe Acute Respiratory Syndrome in early 2003. We focused on issues that affected the population's willingness to comply with quarantine. Information was acquired from interviews, telephone polling, and focus groups. Issues of quarantine legitimacy, criteria for quarantine, and the need to allow some quarantined healthcare workers to leave their homes to go to work were identified. Also important was the need to answer questions from people entering quarantine about the continuation of their wages, salaries, and other forms of income while they were not working, and about the means by which they would be supplied with groceries and other services necessary for daily living. The threat of enforcement had less effect on compliance than did the credibility of compliance-monitoring. Fighting boredom and other psychological stresses of quarantine, muting the forces of stigma against those in quarantine, and crafting and delivering effective and believable communications to a population of mixed cultures and languages also were critical. The need for officials to develop consistent quarantine policies, procedures, and public messages across jurisdictional boundaries was paramount.     

用差分方程模型模拟北京2003年SARS疫情

根据北京2003年SARS疫情发展的实际情况,利用差分方程建立模拟北京疫情发展过程(2003年3月20日至7月14日)的数学模型．建立主要由模拟值与实际统计值之差的平方和构成的目标函数．最后利用Gauss-Newton最优化方法,对模型中参数进行估计．     

Preparedness for an anthrax attack

Bacillus anthracis is a long-known bacterial organism with a uniquely stable spore stage. Its stability and the lethal disease which results when the spore is inhaled made it a favorite of state-sponsored biological weapons programs throughout the Cold War era. It is also believed to be high on the list of candidate microbial agents which could be used by terrorist groups or lone actors. Its unique characteristics make protection of humans, especially civilians, from an intentional biological attack very difficult. The author argues that an all-hazards/public health approach – which would also be needed for any natural or deliberate outbreak, no matter the agent – should serve as a foundation of preparation for the specific anthrax countermeasures. Because B. anthracis is a unique organism, specific countermeasures for anthrax detection, diagnostics, prophylaxis and therapy, should be developed in nations or regions where the threat of biological attack is believed to warrant such preparation. Other considerations for a nation interested in anthrax preparedness are discussed.     

Impact of quarantine on the 2003 SARS outbreak: a retrospective modeling study

During the 2003 Severe Acute Respiratory Syndrome (SARS) outbreak, traditional intervention measures such as quarantine and border control were found to be useful in containing the outbreak. We used laboratory verified SARS case data and the detailed quarantine data in Taiwan, where over 150,000 people were quarantined during the 2003 outbreak, to formulate a mathematical model which incorporates Level A quarantine (of potentially exposed contacts of suspected SARS patients) and Level B quarantine (of travelers arriving at borders from SARS affected areas) implemented in Taiwan during the outbreak. We obtain the average case fatality ratio and the daily quarantine rate for the Taiwan outbreak. Model simulations is utilized to show that Level A quarantine prevented approximately 461 additional SARS cases and 62 additional deaths, while the effect of Level B quarantine was comparatively minor, yielding only around 5% reduction of cases and deaths. The combined impact of the two levels of quarantine had reduced the case number and deaths by almost a half. The results demonstrate how modeling can be useful in qualitative evaluation of the impact of traditional intervention measures for newly emerging infectious diseases outbreak when there is inadequate information on the characteristics and clinical features of the new disease-measures which could become particularly important with the looming threat of global flu pandemic possibly caused by a novel mutating flu strain, including that of avian variety.     

Epidemiology, transmission dynamics and control of SARS: the 2002-2003 epidemic

This paper reviews current understanding of the epidemiology, transmission dynamics and control of the aetiological agent of severe acute respiratory syndrome (SARS). We present analyses of data on key parameters and distributions and discuss the processes of data capture, analysis and public health policy formulation during the SARS epidemic are discussed. The low transmissibility of the virus, combined with the onset of peak infectiousness following the onset of clinical symptoms of disease, transpired to make simple public health measures, such as isolating patients and quarantining their contacts, very effective in the control of the SARS epidemic. We conclude that we were lucky this time round, but may not be so with the next epidemic outbreak of a novel aetiological agent. We present analyses that help to further understanding of what intervention measures are likely to work best with infectious agents of defined biological and epidemiological properties. These lessons learnt from the SARS experience are presented in an epidemiological and public health context.     

Congruent epidemic models for unstructured and structured populations: analytical reconstruction of a 2003 SARS outbreak

Both the threat of bioterrorism and the natural emergence of contagious diseases underscore the importance of quantitatively understanding disease transmission in structured human populations. Over the last few years, researchers have advanced the mathematical theory of scale-free networks and used such theoretical advancements in pilot epidemic models. Scale-free contact networks are particularly interesting in the realm of mathematical epidemiology, primarily because these networks may allow meaningfully structured populations to be incorporated in epidemic models at moderate or intermediate levels of complexity. Moreover, a scale-free contact network with node degree correlation is in accord with the well-known preferred mixing concept. The present author describes a semi-empirical and deterministic epidemic modeling approach that (a) focuses on time-varying rates of disease transmission in both unstructured and structured populations and (b) employs probability density functions to characterize disease progression and outbreak controls. Given an epidemic curve for a historical outbreak, this modeling approach calls for Monte Carlo calculations (that define the average new infection rate) and solutions to integro-differential equations (that describe outbreak dynamics in an aggregate population or across all network connectivity classes). Numerical results are obtained for the 2003 SARS outbreak in Taiwan and the dynamical implications of time-varying transmission rates and scale-free contact networks are discussed in some detail.     

Expert Views on Regulatory Preparedness for Managing the Risks of Nanotechnologies

The potential and promise of nanotechnologies depends in large part on the ability for regulatory systems to assess and manage their benefits and risks. However, considerable uncertainty persists regarding the health and environmental implications of nanomaterials, hence the capacity for existing regulations to meet this challenge has been widely questioned. Here we draw from a survey (N=254) of US-based nano-scientists and engineers, environmental health and safety scientists, and regulatory scientists and decision-makers, to ask whether nano experts regard regulatory agencies as prepared for managing nanomaterial risks. We find that all three expert groups view regulatory agencies as unprepared. The effect is strongest for regulators themselves, and less so for scientists conducting basic, applied, or health and safety work on nanomaterials. Those who see nanotechnology risks as novel, uncertain, and difficult to assess are particularly likely to see agencies as unprepared. Trust in regulatory agencies, views of stakeholder responsibility regarding the management of risks, and socio-political values were also found to be small but significant drivers of perceived agency preparedness. These results underscore the need for new tools and methods to enable the assessment of nanomaterial risks, and to renew confidence in regulatory agencies’ ability to oversee their growing use and application in society.     

The experience of the 2003 SARS outbreak as a traumatic stress among frontline healthcare workers in Toronto: lessons learned

The outbreak of severe acute respiratory syndrome (SARS) in the first half of 2003 in Canada was unprecedented in several respects. Understanding the psychological impact of the outbreak on healthcare workers, especially those in hospitals, is important in planning for future outbreaks of emerging infectious diseases. This review draws upon qualitative and quantitative studies of the SARS outbreak in Toronto to outline the factors that contributed to healthcare workers' experiencing the outbreak as a psychological trauma. Overall, it is estimated that a high degree of distress was experienced by 29-35% of hospital workers. Three categories of contributory factors were identified. Relevant contextual factors were being a nurse, having contact with SARS patients and having children. Contributing attitudinal factors and processes were experiencing job stress, perceiving stigmatization, coping by avoiding crowds and colleagues, and feeling scrutinized. Pre-existing trait factors also contributed to vulnerability. Lessons learned from the outbreak include: (i) that effort is required to mitigate the psychological impact of infection control procedures, especially the interpersonal isolation that these procedures promote; (ii) that effective risk communication is a priority early in an outbreak; (iii) that healthcare workers may have a role in influencing patterns of media coverage that increase or decrease morale; (iv) that healthcare workers benefit from resources that facilitate reflection on the effects of extraordinary stressors; and (v) that healthcare workers benefit from practical interventions that demonstrate tangible support from institutions.     

Modelling strategies for controlling SARS outbreaks

Severe acute respiratory syndrome (SARS), a new, highly contagious, viral disease, emerged in China late in 2002 and quickly spread to 32 countries and regions causing in excess of 774 deaths and 8098 infections worldwide. In the absence of a rapid diagnostic test, therapy or vaccine, isolation of individuals diagnosed with SARS and quarantine of individuals feared exposed to SARS virus were used to control the spread of infection. We examine mathematically the impact of isolation and quarantine on the control of SARS during the outbreaks in Toronto, Hong Kong, Singapore and Beijing using a deterministic model that closely mimics the data for cumulative infected cases and SARS-related deaths in the first three regions but not in Beijing until mid-April, when China started to report data more accurately. The results reveal that achieving a reduction in the contact rate between susceptible and diseased individuals by isolating the latter is a critically important strategy that can control SARS outbreaks with or without quarantine. An optimal isolation programme entails timely implementation under stringent hygienic precautions defined by a critical threshold value. Values below this threshold lead to control, but those above are associated with the incidence of new community outbreaks or nosocomial infections, a known cause for the spread of SARS in each region. Allocation of resources to implement optimal isolation is more effective than to implement sub-optimal isolation and quarantine together. A community-wide eradication of SARS is feasible if optimal isolation is combined with a highly effective screening programme at the points of entry.     

SARS Research in China

SARS Research in China     

抗体与SARS研究

在非典型性肺炎（SARS）的研究过程中,抗体无论在临床医学领域,还是在基础病毒学研究领域都发挥着重要的作用。利用重组蛋白或者人工合成的多肽免疫得到的针对SARS病毒特异性的单克隆、多克隆抗体可以用于SARS病人的临床血清学检测、SARS的预防治疗,还可以用于病毒蛋白的功能性研究。因此,抗体在类似SARS这样的感染性疾病研究过程中有着极大的应用价值。