Pandemic influenza planning: using the U.S. Centers for Disease Control FluAid Software for small area estimation in the Canadian context

Purpose The U.S. Centers for Disease Control and Prevention (CDC) developed software (FluAid 2.0) to provide estimates of pandemic impact (deaths, hospitalizations, and outpatient visits). We wished to develop inputs for Alberta, Canada to use in place of program default values. We also wished to examine how FluAid output could be better contextualized for local users. Methods We developed distributions for age and age-sex specific proportions of population in groups at high risk of influenza complications for Alberta, Canada. In addition, we developed interpandemic influenza rates for Alberta, Canada. We used FluAid with this local data to obtain estimations of both pandemic and interpandemic impacts of influenza. The ratio of these impacts presents a context for understanding the FluAid outputs. Results There were differences in both the pattern and the magnitude of the Alberta rates from the FluAid defaults. For a pandemic estimate at a 25% attack rate (most likely) compared to an interpandemic year, the pandemic would result in 3.7 times as many outpatient visits, 3.9 times as many hospitalizations and 8.2 times as many deaths. Conclusion We recommend that health service planners who use FluAid develop estimates for interpandemic influenza to provide crucial contextual information for pandemic planning.