A new commentary in BMJ's Clinical Evidence challenges the dogma that seasonal influenza is a relatively common infection. The author uses data from the control arms of 95 influenza vaccine trials involving 1 million subjects over the course of four decades to demonstrate his point. The bottom line is that 7% percent of the population will develop influenza-like illness (ILI) yearly; however, only 7% of the group with ILI actually have influenza, with the remaining 93% infected with other pathogens. So doing the math (0.07 x 0.07 x 100), you can see that only 0.5% of the population develops influenza yearly. To be clear, these data are for seasonal, not pandemic, influenza, so we would not expect these data to be applicable to the current situation in the US. Nonetheless, I'm astounded by this analysis.