Experts ponder why regular flu season is a no-show

The flu season has gone missing, and experts are trying to figure out what happened.

After spreading swiftly in the summer and fall, swine flu has all but disappeared. And the regular outbreak of influenza that usually hammers hundreds of thousands of people by this time every year has yet to happen. In late February, flu inspired 1.8 percent of all visits to the doctor, according to the latest figures from the CDC. And that's well below the norm.

It's not the result of a major vaccination campaign, says Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota. There are multitudes of people in the U.S. who have not been vaccinated or infected. Some of the experts attribute the odd lull to the earlier spike in swine flu cases, noting that influenza typically rolls through a country in waves. Others suspect swine flu spurs a chemical that provides some level of immunity.

Regardless, flu watchers aren't letting down their guard. Influenza experts will stay alert to any new outbreaks, ready to rush vaccine where it may be needed. And, unlike previous years, there's no shortage of shots to report.

- here's the story from the Wall Street Journal