Use of Predictive Disease Modeling in Los Angeles County: Planning for and Responding to Pandemic Influenza

Planning for pandemic influenza is a significant challenge, particularly in a large urban community. To improve planning and response outcomes, Los Angeles County employed robust disease simulation models to validate and focus local strategies and plans. Initially designed for a H5N1 like scenario, the model was quickly and continuously adjusted during H1N1 to improve response efforts. The use of the model required four steps: 1-Build a synthetic version of the community; 2-Utilize best available epidemiological data; 3-Apply realistic intervention strategies; 4-Adjust simulations to identify most effective response policies. To increase model utility the best available data was incorporated, including: latest census estimates; commuter data and transportation patterns; age dependent transmission probability rates, range of Ro (1.2 – 2.1) and numerous vaccine, anti-viral and non-pharmaceutical distribution strategies; all based on local capacities. The results improved pandemic influenza planning in three ways: 1-Oriented Vaccination Plans: Vaccination of school age children is most effective way to mitigate spread throughout community; also quantified the effects of delayed vaccine distribution. 2-Validated School Closure Strategies. Closures and dismissals—unless hyper aggressive and sustained—are ineffective. 3-Influenced Innovative Response. Early, targeted prophylactic use of anti-viral countermeasures—via household contacts of confirmed ill—can dampen community transmission. A myriad of issues challenge effective pandemic planning and response. This modeling process provides an effective tool to quantify threats, evaluate intervention capabilities and create plans and policies to guide operational response actions. While specific to pandemic influenza in Los Angeles, the application to other jurisdictions and diseases is a prudent consideration.