An airborne bioterrorist attack must occur in a place where the BioWatch system is deployed and with a biological agent that BioWatch air samplers and laboratory test methods can detect.
Atmospheric conditions must disseminate the material in a way that exposes people to a viable pathogenic biological agent.
Atmospheric conditions must disseminate the material in the direction of the BioWatch air samplers, resulting in sufficient quantities reaching their filters to allow detection.
The samplers must function as anticipated; samples must be collected, managed, and tested appropriately to allow for detection of the genetic signature of the biological agent; and positive results must be reported to public health authorities in time to allow for any assessment that must be made before a decision regarding mass prophylaxis can be reached.
Public health and other authorities must collaborate effectively in conducting an assessment of the likelihood that the positive test indicates a bioterrorist attack and a population health risk, based on the mix of factors that may shape such assessments (see Chapter 2); and, taken together, the correct conclusion must be made that mass dispensing is indicated.
Infection with the biological agent can be successfully prevented or treated with the drugs or other medical countermeasures that could be used in the mass prophylaxis program.
State or local public health systems must be able to deliver mass prophylaxis in time for its benefits to be realized; depending on the disease-causing agent and the size of the exposed population, this may involve providing prophylaxis within 2–3 days to several million people.
As noted in Chapter 1, evaluation of the likelihood of an airborne biological attack that could be detected by the BioWatch system is beyond the committee’s scope, as is an evaluation of the ability of public health officials to deliver mass prophylaxis in a limited time period. Here, the committee evaluates elements of the BioWatch system that are necessary, if not sufficient, for the system to be effective, including the air samplers and their placement, the samplers’ capture of targeted organisms, the laboratory assays, information reporting, event characterization, and public health decision making.
The committee considered information provided by DHS regarding the separate components of the BioWatch system, as well as information relevant to the operational capabilities of the components working together.