In reply to JH Morehouse.

JH, I don’t think you’re being obtuse, just cautious. The interesting thing is that Google’s graph for the past few years of data seems to overlap quite precisely with the CDC’s. It would seem that regardless of whether people who type “flu” are sick themselves, the one correlates with the other. Whether that will continue to hold in the future, now that the specific scare of H1N1 is upon us, remains to be seen.