Lesson?
Leaving aside the usual insane counter-contribution of the media, and thinking solely of the rational public-health response to the Mexican flu...
Seems like a strong argument for fully networked electronic medical records, covering every place that has modern hospitals.
The initial information from Mexico, based largely on rumor and anecdote, led CDC and WHO to switch into high-alert mode, which was proper at that moment. After a few days, it became clear that the high death rate in Mexico did not indicate a deadly serious virus, but rather a combination of other illnesses with a typical death rate from a large number of flu cases.
Now the CDC is trying to back away from the red alert without ruining its credibility, but the credibility is already trash.
If the correct information had been instantly available from Mexican and Texas hospitals, CDC and WHO could have given a more moderate response at the start.