U.S. health officials say the flu vaccine seems to be working pretty well this season.
Preliminary data suggest the vaccine is 48 percent effective. That's not bad since the bug that's making most people sick is one of the worst. Experts consider it a good year when a flu vaccine is 50 to 60 percent effective.
The flu vaccine is changed each year based on the best guess at which strains will be the biggest problem. Officials say the current vaccine is a good match.
The U.S. flu season usually peaks in midwinter. Cases are escalating in some parts of the country, but already receding in others.