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.
via Experts ponder why regular flu season is a no-show – FierceVaccines.