Shrestha, S., Swerdlow, D., Borse, R., et al. (2011). Estimating the Burden of 2009 Pandemic Influenza A (H1N1) in the United States (April 2009-April 2010). Clinical Infectious Diseases. 52(suppl_1):S75-S82.
The authors modeled the number of cases, hospitalizations, and deaths due to 2009 H1N1 to address likely underreporting and compared these estimates to those for seasonal influenza. They found that the rates of hospitalizations and deaths among those under 65 were higher than for seasonal influenza while the rates of hospitalization were 75 percent lower and deaths 81 percent lower among those 65 and older in comparison to seasonal influenza.