Ethical and Legal Considerations in Mitigating Pandemic Disease Workshop Summary (2007) / Chapter Skim
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3 Strategies for Disease Containment
3 Strategies for Disease Containment
Pages 76-153
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From page 76... ...
The authors of the first three papers raise a variety of legal and ethical concerns associated with behavioral approaches to disease containment and mitigation that must be addressed in the course of pandemic planning, and the last three papers describe the use of computer modeling for crafting disease containment strategies. More specifically, the chapter's first paper, by Lawrence Gostin and Benjamin Berkman of Georgetown University Law Center, presents an overview of the legal and ethical challenges that must be addressed in preparing for pandemic influenza.
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From page 77... ...
The authors identify various means to address this tension and offer examples of how ethical considerations can be incorporated into pandemic preparedness plans. The chapter concludes with a three-part contribution by Joshua Epstein of the Brookings Institution: an informal discussion of the modeling process as it applies to infectious disease containment, followed by two publications in which such models are used to inform strategies for containing smallpox epidemics resulting from bioterrorism.
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O'Neill Chair in Global Health Law, Georgetown University Law Center; Professor of Public Health, the Johns Hopkins University; Faculty Director, O'Neill Institute for National and Global Health Law at the Georgetown University Law Center; Director, Center for Law and the Public's Health, a Collaborating Center of the World Health Organization and Centers for Disease Control and Prevention. 3 Sloan Fellow in Biosecurity Law and Policy, Center for Law and the Public's Health.
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. One study that extrapolates from the severe 1918 pandemic finds that, in the absence of intervention, an influenza pandemic could lead to 1.9 million deaths in the United States and 180 million to 369 million deaths globally (Osterholm, 2005)
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. This document purports to be a "checklist to help medical offices and ambulatory clinics assess and improve their preparedness for responding to pandemic influenza." However, it does not address the myriad legal and ethical issues that will arise.
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Experimental H5N1 vaccines may not be effective against a novel human subtype, and the pathogen may become resistant to neuraminidase inhibitors. Public Health Countermeasures Given the limits of medical countermeasures, a broad range of public health would likely be employed against an influenza pandemic, from relatively innocuous techniques, such as disease surveillance and hygienic measures, to considerably more restrictive interventions, such as social distancing, travel restrictions, quarantine, and case isolation.
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Community Hygiene and Hospital Infection Control Hygienic measures to prevent the spread of respiratory infections are broadly accepted and have been widely used in both influenza pandemics (APHA, 1918) and also, although with uncertain benefits, the SARS outbreaks (WHO, 2003; CDC, 2005a)
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From page 83... ...
Predicting the effect of policies to increase social distance is difficult, as infected persons and their contacts may be displaced into other settings, and individuals may voluntarily separate in response to perceived risk. For these reasons, additional research needs to be conducted on behavior during epidemics and the effects of social distancing on transmission.
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Ideally, questions of government authority and accountability should be answered by policy decisions made in an open and transparent process that encourages input from all portions of society and that is carried out before a pandemic hits. Governments should explicitly define who has the power to order social distancing strategies and for what period of time.
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Workplace and School Closings Workplace and school closings present particularly difficult ethical issues. Apart from the uncertainty of their effectiveness, the most important issues center on the subject of distributive justice.
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Even if the resources are available, the workforce needed to conduct distribution may be absent, especially at the height of a pandemic when a substantial number of people would be ill. Furthermore, there may not be enough people willing to interact closely with potentially infectious people to allow such a system to function.
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International Trael and Border Controls Transnational public health law has become increasingly important in global health, as evidenced by the WHO's International Health Regulations and by national health agencies' proposed communicable disease regulations (HHS, 2005a)
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Given that they involve a significant deprivation of an individual's liberty in the name of public health, quarantine and isolation expose the tension between the interests of society in protecting the health of its citizens and the civil liberties of individuals, such as privacy, non-discrimination, freedom of movement, and freedom from arbitrary detention. Although these civil liberties are protected by both universal and regional human rights declarations and conventions, large-scale public health threats can require extraordinary measures by the government.
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A pandemic influenza will require solidarity among nations and collaborative approaches that set aside traditional values of self-interest and territoriality. Conclusion Preparing for an influenza pandemic forces society to face a number of difficult challenges, many of which transcend the issue of mere scientific effective
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ETHICAL AND LEGAL CONSIDERATIONS IN PREPARING FOR PANDEMIC INFLUENZA9 James W LeDuc, Ph.D.0 Centers for Disease Control and Prevention Drue H
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For this reason public health officials must apply ethical reasoning on matters for which the law does not provide precise guidance. In particular, such ethical considerations should inform officials' deliberations when making difficult choices that directly affect the health and well-being of the populations they serve.
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Public health officials have a responsibility to maximize preparedness in order to minimize the necessity for making allocation decisions later, during the course of the pandemic. Ethical guidelines should be based on the best available scientific evidence, with the current knowledge base serving as a foundation for these guidelines.
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Another important component of pandemic influenza planning will be resource allocation. The guidelines suggest that resource allocation should be designed to accomplish clearly articulated goals and be guided by criteria specified well in advance of a pandemic.
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Social distancing and restrictions on personal freedom will be important tools for managing pandemic influenza. Such interventions can include the isolation of infected individuals; the quarantine of those heavily exposed, such as family members or close contacts; adjustments to school schedules or even the closing of schools and cancellation of public events; limiting travel; and restricting access to public venues.
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Table 3-2 lists a variety of issues related to public health law that will influence the effectiveness of mandatory social distancing, arranged according to the framework of the four public health legal-preparedness core elements. Table 3-3 presents a number of questions about and challenges relating to the level of legal preparedness for social distancing.
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ETHICAL AND LEGAL CONSIDERATIONS IN MITIGATING PANDEMIC DISEASE TABLE 3-2 Selected Public Health Law-Related Issues and Needs for Effective Mandatory Social Distancing Legal Authorities to: • Quarantine/isolate individuals and groups • Modify the schedules of or close schools and public meetings • Restrict commercial movement Public and Private Officials Competent in: • Application of social-distancing legal powers • Protection of individual and property rights • Legal responsibilities of health-care providers Coordination of Legal Tools Across Jurisdictions and Sectors: • Public health coordination with emergency response and law-enforcement agencies • Public health coordination with health-care providers • Coordination of social-distancing measures across communities and states Information Resources on: • Legal best practices in social distancing • Effective communication of legal basis for social distancing with the public and the media TABLE 3-3 Selected Challenges to Legal Preparedness for Social Distancing Legal Authorities: • Landscape of state/local laws is incompletely known • Unclear if laws (e.g., school closure) are uniform • Concern that laws may not provide due process, civil liberties, and property-rights protections Competencies: • Ensuring that officials of public health and other agencies are trained in use of social distancing legal powers • Ensuring that private health-care providers understand their legal responsibilities during pandemics • Ensuring that public and private officials participate in tests of social-distancing legal preparedness Coordination: • Unclear if states can assist enforcement of federal quarantine • Lack of protocols -- e.g., between public health, law enforcement, and health care -- for coordinated, cross-sector response Information Resources: • Guidance on sectors' roles and responsibilities • Guidance for communicating with the public and the media
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From page 97... ...
These core elements of public health legal preparedness for pandemic influenza should be tested in every community and state by conducting exercises and other approximations of an actual pandemic. Such tests can help local and state officials and their private-sector counterparts identify gaps in legal authorities for mandatory social distancing, in case it should be needed, and also help them ascertain whether protocols are in place to translate those powers into practice.
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Because the scientific data needed for informed decision making are incomplete, models have been used extensively to predict outcomes based on representative scenarios of an influenza pandemic. These increasingly sophisticated models have proven valuable in exploring the possible outcomes of various policy decisions (IOM, 2006)
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Pandemic Influenza Plan issued in November, 2005 (HHS, 2006a) .22 The purpose of this article is to review the modern public health approach to quarantine, outline highlights of current plans for its implementation in the event of an avian influenza pandemic, and consider the ethical principles that should be considered.
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. Modern public health places quarantine within a broader spectrum of interventions generally referred to as "social distancing." The effect of successful measures to increase social distance is to convert a dynamic of exponentiation in the spread of an infectious agent to one of suppression in which the number of secondary cases from exposed persons is reduced to a manageable level.
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A recently developed Model State Emergency Health Powers Act attempts to promote greater interstate consistency in response to emergency public health situations (Center for Law and the Public's Health, 2001)
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Public health, on the other hand, emphasizes collective action for the good of the community. The Principles of the Ethical Practice of Public Health, issued by the Public Health Leadership Society in 2002 (Public Health Leadership Society, 2002)
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Fourth, the obligation of public health authorities is to communicate the reasons for their actions and to allow for a process of appeal. In November 2004, the World Health Organization issued a checklist for influenza pandemic preparedness.
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. The guide identified four key ethical issues in pandemic preparedness planning, one of which was "restricting liberty in the interest of public health by measures such as quarantine." The guide describes the following substantive and procedural ethical values at stake in addressing this issue: 1.
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Careful attention to the ethical values at stake in public health decision making can help foster voluntary cooperation and public trust and should be a part of state and federal pandemic preparedness planning. REMARKS ON THE ROLE OF MODELING IN INFECTIOUS DISEASE MITIGATION AND CONTAINMENT Joshua M
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. Accordingly, I build explicit models, and we at NIH/MIDAS build explicit models, so that we can study exactly what our assumptions entail: On these assumptions, this sort of thing happens.
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, and hemorrhagic smallpox before comparing intervention strategies (see below)
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As I will show you, there are actual social networks governing who bumps into whom. The Smallpox Model The smallpox model was initiated by me and Donald Burke,28 then of the Johns Hopkins Bloomberg School, at the invitation of the National Academy of Sciences' Committee on International Security and Arms Control (CISAC)
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However, to reinforce my earlier point about the need for close collaboration between modelers and medical experts, the Working Group had intensive regular meetings to arrive at detailed assumptions about all the biomedical and critical behavioral aspects of this problem, and when I say "detailed assumptions," I really mean it. Figure 3-1 shows the natural history assumptions we arrived at for ordinary smallpox.
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0 ETHICAL AND LEGAL CONSIDERATIONS IN MITIGATING PANDEMIC DISEASE Landscape view FIGURE 3-1 Ordinary smallpox natural history. SOURCE: Longini et al.
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Neither modeling in isolation nor expert opinion unsupported by models would have had the combined scientific and policy impact this collaboration achieved. We aim to replicate this excellent experience on global pandemic flu within
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Copyright Elsevier 2006. Original article was in International Journal of Infectious Disease 11(2)
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From page 113... ...
. Other work, not based on a dynamic epidemic model, suggests that given the small probability of a bioterrorist smallpox attack, preemptive mass vaccination is not a good strategy as opposed to reactive containment strategies (Bozzette et al., 2003)
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From page 114... ...
We also examine the added benefit of prevaccination of hospital workers, reactive mass vaccination of the population after an attack has been detected, and reactive closing of the schools. Materials and Methods Many of the parameters and scenarios of our model were determined by the Smallpox Modeling Working Group, the Secretary's Advisory Council on Public Health Preparedness, Department of Health and Human Services.36 Parameter values and modeling decisions made by the working group were based on the group's collective knowledge of smallpox epidemiology and on information from Chapter 4 of Smallpox and its Eradication by Fenner et al.
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Hemorrhagic smallpox was modeled to have a shorter natural history and more severe disease progression than ordinary smallpox with a 100 percent case fatality rate (Figure 3-5)
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, smallpox is known to be present and all ordinary smallpox would be recognized in the hospital on the third continued
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. We define x as the probability that an infected person with ordinary smallpox, on the second day after the onset of fever, makes sufficient contact to infect an unvaccinated susceptible person in the mixing group being modeled.
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The infectiousness of people with modified smallpox would be 33 percent of that for people with ordinary smallpox, with a case fatality rate of 10 percent. However, it would be harder to recognize modified smallpox and cases would be slower to withdraw to the home or go to the hospital than for ordinary smallpox.
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Infected people would begin internal bleeding four days after the onset of fever, and 100 percent would die on the seventh day after the onset of bleeding. Before smallpox is recognized, we assumed that 50 percent of hemorrhagic smallpox cases would not be recognized and 50 percent would be recognized on the fifth day of fever.
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(A) The 2000 person subpopulations consist of households and household social clusters depicted by the connecting lines in neighborhood 2.
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Each day, for each susceptible, the probability of becoming infected is calculated based on his vaccination status, who is infectious in his or her mixing groups, and his or her vaccination status, as well as the mixing group-specific transmission probabilities. As an example, consider the simplest case that no one is vaccinated and we ignore the complex natural history of smallpox for illustrative purposes.
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From page 122... ...
For those vaccinated between 5–7 days post-infection, 60 percent would develop modified smallpox, 38 percent ordinary smallpox, and 2 percent hemorrhagic smallpox. Vaccination reduces the death rate of breakthrough infections, for old vaccinations or fresh vaccinations 4–7 days post-infection, to a very low level, i.e., 1 percent or less.
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Scenario 3 was surveillance and containment (with vaccination of close contacts) alone, and then scenarios 4–10 involved surveillance and containment plus various additional control measures including pre-emptive vaccination of hospital workers, reactive mass vaccination, and reactive school closings.
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TABLE 3-5 Smallpox Simulation Scenarios Scenario 1 2 Baseline 3 4 5 6 7 8 9 10 Background immunity +a + + + + + + + + + Surveillance and containment Isolation but no vaccination + + + + + + + + Pre-emptive vaccination Pre-emptive vaccination (hospital only) 10% 50% 10% 50% 10% 50% 10% Reactive school closure, 10 days + + + + + Mass reactive vaccination 40% 40% 80% 80% aThe + indicates that the factor is present.
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, then the average number of cases would be reduced to 828 and the number of deaths to 211. Figure 3-8A indicates that for surveillance and containment there would be a relatively large second wave of cases after the initial wave, and then a much smaller third FIGURE 3-7 A plot showing the relationship between the transmission probability x during the second day of fever from an unvaccinated case of smallpox to an exposed unvaccinated person in a mixing group and the maximum household secondary attack (SAR)
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(B) Epidemic with 3-8 surveillance and containment, 50 percent preemptive hospital vaccination and 80 percent reactive mass vaccination with reactive school closure for ten days (scenario 9)
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Under surveillance and containment (scenario 3) , an average of 7,501 fresh doses of vaccine would be used, far fewer than the ~25,500 doses that would be used under 40 percent reactive mass vaccination plus surveillance and containment and preemptive hospital vaccination (scenarios 6 and 7)
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From page 128... ...
~45,000 doses that would be used under 80 percent reactive mass vaccination plus surveillance and containment and preemptive hospital vaccination (scenarios 8 and 9)
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From page 129... ...
If logistically possible, implementation of reactive mass vaccination would make sense. Prevaccination of hospital workers results in somewhat smaller outbreaks in the event of an attack.
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The most sensitive factor was timing of withdrawal to the home and isolation of cases. A delay in recognition of cases by one or more days beyond the hypothesized control strategy outlined in Figures 3-3 through 3-5 was found to result in poorly contained simulated epidemics (Table 3-10)
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From page 131... ...
Acknowledgment This research was partially funded by the Fogarty International Center, National Institute of Allergy and Infectious Disease grant R01AI32042, and the National Institute of General Medical Sciences MIDAS grant U01GM070749. Conflict of interest: No conflict of interest to declare.
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2006. Individual-based computational modeling of smallpox epidemic control strategies.
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From page 133... ...
Department of Health and Human Services Secretary's Advisory Council on Public Health Preparedness. The charge to members of the working group was to modify their existing smallpox epidemic models to incorporate agreed-on values for the natural history and transmission of the disease and then use the model to analyze epidemic outcomes under a variety of plausible attack and response scenarios.
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. Other parameters, such as the probability of smallpox transmission per contact at various phases of the disease's natural history, and contact rates per day in various social units (the home, school, workplace, and hospital)
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Scenario 2 was identical to scenario 1 except that transmission from hospitalized persons was set at zero to determine if the force of infection in the community alone was sufficient to sustain the simulated epidemics. Ealuation of "Response" Scenarios We then conducted an analysis of eight response scenarios specified by the working group.
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(B) Town social architectures of single uniform, ring, and hub-and-spoke 3-9 structure.
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Instead of 35 simulated epidemic runs per scenarioarchitecture pair, we present the statistics for just ten stochastic realizations. Results Ta�ular Results Cases, deaths, vaccinations, and epidemic durations for simulated epidemics under the two "no response" and the eight response scenarios are shown in Tables 3-11 and 3-12 (see Annex 3-1)
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FIGURE 3-10 Summary sketch of the interventions and combinations of baseline conditions and interventions studied in "no response" scenarios 1 and 2 and response scenarios 3-10. Landscape view fig 3-10
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While reactive mass vaccination was effective in reducing the number of infections, the number of vaccinations per infected person was substantially greater under these scenarios (scenarios 6–9)
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From page 140... ...
. Although these scenarios yielded smaller and shorter epidemics than response scenarios based on isolation, contact tracing, and targeted vaccination alone, the largest difference attributable to mass vaccination in the 6,000-person town was a reduction from 45.9 to 17.3 cases (scenario 4 [no mass vaccination]
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From page 141... ...
In accordance with the values proposed by the working group expert advisors, cases were assigned one of three different clinical disease expressions: ordinary smallpox, modified smallpox, or hemorrhagic smallpox. Among all of the smallpox cases that occurred in these 35 simulated epidemic runs, 57 percent were ordinary, 40 percent were modified, and 3 percent were hemorrhagic cases.
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(B) Epidemic reproductive rate for each clinical disease type at each epidemic generation.
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In both size versions of the model, reactive mass vaccination at the town level had additional value in bringing an epidemic under control. We estimate the number of reactive mass vaccinations required to incrementally reduce the epidemic by one case to be about 190 vaccinations in the 6,000person town/10-attack-case model versions and about 35 vaccinations in the more intense 50,000-person town/500-attack-case model version.
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From page 144... ...
Conclusions Our simulation exercise revealed that contact tracing and vaccination of household, workplace, and school contacts, along with prompt reactive vaccination of hospital workers and isolation of diagnosed cases, could contain smallpox at both epidemic scales examined. Individual-based simulations of smallpox epidemics provide a valuable tool in crafting policy regarding outbreak response.
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Presentation delivered at Institute of Medicine workshop entitled "Modeling Community Containment of an Influenza Pandemic," Washington, DC. Cetron M, Landwirth J
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2003. Infectious diseases.
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Emerging Infectious Diseases 10(7)
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2006. A Historical Assessment of Nonpharmaceutical Disease Containment Strategies Employed �y Selected U.S.
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2005. Stand on Guard for Thee: Ethical Considerations in Preparedness Planning for Pandemic Influenza.
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Emerging Infectious Diseases 12(1)
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TABLE 3-4 Daily Transmission Probabilities, x,a Among Children and Adults, by Mixing Group, and Group Sizes Children Pre-school School Small Large Contact group Mean size playgroup daycare Elementary Middle High Adults Small playgroupd 2.9 0.03000 Large day-care centers 15.8 0.02000 Elementary school 77.8 0.01000 Middle school 145.3 0.00800 0.00800 High school 113.7 Family 2.5 Child 0.03520 0.03520 0.03520 0.03520 0.03520 0.01240 Adult 0.01240 0.01240 0.01240 0.01240 0.01240 0.01510 Household social cluster 10.1 Child 0.03000 0.03000 0.03000 0.03000 0.03000 0.01000 Adult 0.01000 0.01000 0.01000 0.01000 0.01000 0.01000 Hospital Smallpox ward 133.0 Worker-worker 0.00200 Worker-visitor 0.00200 0.00200 0.00200 0.00200 0.00200 0.00200 Patient-worker 0.00010 0.00010 0.00010 0.00010 0.00010 0.00010 Patient-visitor 0.00010 0.00010 0.00010 0.00010 0.00010 0.00010 Other wards 533.0 0.00050 Workgroup 0.01000 Neighborhood 500.0 0.00004 0.00004 0.00005 0.00005 0.00005 0.00014 Community 2000.0 0.00001 0.00001 0.00001 0.00001 0.00001 0.00003 aThe probability that an infected person with ordinary smallpox, on the second day after the onset of fever, makes sufficient contact to infect an unvaccinated susceptible person in the mixing group being modeled.
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(10.0) Data from single uniform town, ring town, and hub-and-spoke town architectures are shown.
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From page 153... ...
(11.1) Data from simulations on the single uniform town and ring town architectures are shown (simulations on the hub-and-spoke town architecture were not performed for the 50,000-person town)
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