A Decision Analysis of State Public Health System Responses to Pertussis Outbreaks

Background:
In order to control an outbreak of pertussis, chemoprophylaxis of close contacts is one of the first measures used to prevent secondary transmission. While this method can reduce the transmission of pertussis, it imposes a significant resource burden on the state public health system (SPHS), which must track and follow up with large numbers of close contacts. Furthermore, there is a general concern associated with widespread use of chemoprophylaxis because of antibiotic resistance. Our motivation for this study is that chemoprophylaxis of close contacts may provide little benefit while consuming a large portion of public resources.

Objectives:
The objective of our decision analysis is to evaluate alternative outbreak control strategies, including vaccination, from the SPHS perspective using public health and economic outcomes.

Methods:
The SPHS incorporates all state public health resources used to respond to a pertussis outbreak. This includes laboratories, local health departments, and state health departments. Our model excludes private health care costs in order to focus on the limited resources available to the SPHS. We model SPHS strategies that allow the state to vary the both number of close contacts and the type of intervention used. After choosing the number of close contacts, the SPHS chooses an intervention strategy: vaccination and chemoprophylaxis, vaccination only, and chemoprophylaxis only. We then compare the current intervention, chemoprophylaxis of all close contacts, to the other intervention strategies. Transmission parameters of pertussis are modeled in a decision tree, with sensitivity analyses and Monte Carlo simulations to test the stability of the results. Costs to a SPHS are based on data from recent pertussis outbreaks.

Results:
This research will inform SPHS decisions through a careful delineation of potential implications of each intervention strategy. Further, the model will be used to inform SPHS decisions when responding to pertussis outbreaks.

Conclusions:
See results section.