Cloudy, With a Chance of Flu

Influenza is a seasonal affair in temperate climates, afflicting populations reliably in the colder months. Exactly when an epidemic will peak, though, has been harder to say. In any given community, it can happen at any time between October and April (in the Northern Hemisphere). That has made planning for the brunt of an outbreak difficult.

Researchers, at last, have come up with a flu-forecasting system that works like the weather report. If used well, the information could mobilize health measures when and where they are needed. Many lives are at stake: Flu kills from 3,000 to 49,000 people in the U.S. every year.