Comparing Severity and Outcomes for Seasonal and 2009 H1N1 Infections—Reply

In Reply: We agree with Dr Adalja that additional data comparing severity and outcomes for seasonal and 2009 H1N1 infections would be informative. However, valid comparisons are difficult in the absence of a stable population and a research infrastructure to ensure consistent screening, enrollment, testing, and data collection across seasons in which different influenza subtypes or strains predominate. We were fortunate that such an infrastructure had been previously established by the US Centers for Disease Control and Prevention (CDC) to support annual estimates of influenza vaccine effectiveness in the Marshfield population. Planning and implementing new research studies within the accelerated time frame of a pandemic is feasible if a pre-existing research platform can be quickly adapted to meet the specific research needs. Thus, an established infrastructure for seasonal influenza studies provides a dual benefit because the resources are not only justified by the assessment of seasonal influenza epidemiology and control measures, but they also enhance the capacity to conduct applied research in a pandemic setting.