The U.S. winter virus season is in full force, and by one measure is the most intense in 15 years.

All four flu pandemics — in 1918, 1957 and 1968 and the swine flu pandemic of 2009 — were caused by Type A viruses. Influenza B viruses, however, only circulate in humans. They are divided ...

Last week, that number was clearly higher than the peak of any winter flu season since 2009-2010, when a swine flu pandemic hit the nation, according to data posted Friday morning by the Centers ...

In 2009 and 2010, swine flu led to more than 12,000 deaths in the U.S.; roughly 10 percent of the victims were under 18. Even if bird flu does no more than it already has, it’ll still cause a ...

Last week, that number was clearly higher than the peak of any winter flu season since 2009-2010, when a swine flu pandemic hit the nation, according to data posted Friday morning by the Centers ...

8 were for flu-like illness, according to the Centers for Disease Control and Prevention (CDC). This continues to be the highest level seen since at least 2009, during the swine flu pandemic.

The most recent CDC Weekly U.S. Influenza Surveillance Report shows that 7.8% of visits to a healthcare provider were for respiratory illness, the worst since the swine flu pandemic in late 2009.