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making cycles. Decision makers also must be informed in advance about the expected limitations of modeling approaches and how uncertainties about existing data may affect model predictions. Detection Capabilities and Diagnostics In the event of a novel outbreak of a high-impact respiratory pathogen, early detection of the event through regular diagnostic testing may not be possible. Routine tests may not properly identify novel diseases. In these circumstances, clinical recognition that something is not normal and rapid reporting of this to appropriate public health authorities would be critical for enlisting the right specialized diagnostic expertise and for mounting a rapid response. In higher-resource countries, specialized diagnostic tools or approaches could be used in efforts to make a rapid initial, pathogen-specific diagnosis of the first patients, with the time to specific diagnosis depending on the pathogen, the samples, the period between recognition of an clinical anomaly, and the initiation of testing. In lower resource settings, or in healthcare settings where clinical anomalies might not be easily evident, it might take substantially longer to initiate the proper testing for a novel pathogen. In those settings, regional, national, or international laboratories might need to be engaged to make an initial specific pathogen diagnosis. Once a pathogen responsible for an emerging epidemic or pandemic is definitively identified as the etiology, the use of diagnostic tools would switch. Diagnostics would no longer be needed for detection, but instead they would be needed for event management. In this latter phase, diagnostics become an important tool in event characterization (determining who is affected, who is at risk of severe outcomes) and in clinical management of patients to optimize treatment and to reduce transmission through proper isolation. 43 In the clinical realm, in a high-resource setting, the approach to a novel diagnosis would be expected to begin with initial confirmation using research-related molecular diagnostics, then would evolve to clinical syndromic surveillance with post facto laboratory confirmation, eventual testing at reference laboratories and major commercial laboratories, and, finally, to widely disseminated diagnostic testing strategies. These processes may be facilitated via pre-established processes to authorize emergency use for nonapproved tests and with national laboratories and public health authorities distributing materials (such as primers) to qualified parties. However, this process is often not seamless nor rapid. In settings without well-developed regulatory frameworks, the process would be more uncertain and depend on local expertise, resources, plans, and perhaps international assistance. With a truly unknown respiratory viral pathogen, initial cases would fail to produce a diagnosis by conventional means, leading to more sophisticated testing, including next-generation sequencing, to identify any clue as to what type of microbe is present and what characterizes it (ie, what viral family it is most closely linked to). In countries with access to such testing, as the diagnostic test is perfected and the etiologic agent better characterized, the development of serological tests to identify past infections as well as simplified molecular diagnostics (and in some cases point-of-care molecular testing) would occur.90 These tests might first be available at national public health labs and may or may not diffuse to local health centers. Limitations would include technical ability as well the availability of materials for the construction of testing, such as nucleic acid primers. In the context of a novel respiratory pathogen, many cases would be diagnosed using clinical scoring criteria, with or without eventual laboratory confirmation. In the event of a deliberate release of a pathogen, the first recognition is likely also to occur following recognition of an anomaly (or anomalies) in the clinical sector, where sick patients are turning up for treatment, with similar processes and challenges to diagnostics as noted above. In addition to clinical diagnostics, assessments of where pathogens may have contaminated the environment could be important for law enforcement activities and efforts at attribution, if there is information available that made such assessments feasible. If these assessments were feasible, then this information could help with determining the scope of initial exposures and determining where there might be environmental contamination. Technological advances are needed to modernize our diagnostic capabilities to become faster and nimbler at the onset of outbreaks, particularly around novel pathogens. Diagnostic tools are required in settings beyond centralized laboratories. Microfluidic devices and other “lab on a chip” devices still in development have the potential to improve diagnostic capacity across a range of settings, shorten the timeline to diagnosis, and ulti- 44 mately trigger a cascade of other actions needed to isolate and characterize the pathogen.91 The window for detection for respiratory pathogens would be very short before transmission may become widespread. As such, the development of these sentinel tools can provide the early detection and warning needed to get ahead of an outbreak. Outbreak Investigation and Response An epidemiologic investigation and the accompanying response are the backbone of outbreak control. As seen currently in the DRC Ebola outbreak, efforts to complete contact tracing in that setting are challenging but critically valuable. Contact tracing is highly effective for outbreaks that are mildly to moderately transmissible and of a modest scope. For high-impact respiratory pathogens, contact tracing would quickly become infeasible. It is very difficult to identify contacts when all who may have been in the general vicinity of a case may be at risk. Furthermore, as the number of potential contacts grows, the resources required to monitor those people quickly would become overwhelming. A 2011 assessment of the economic burden of measles outbreaks, for example, found that each case of measles generated many dozens or even hundreds of contacts, requiring thousands of personnel hours to manage.92
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