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 ...

It's flu season right now, and the U.S. is in the midst of a wave that's straining hospitals. But not all influenza is the ...

New Type of Antibody Shows Promise Against Multiple Forms of Flu Virus Dec. 21 ... A responsible for the 2009 H1N1 pandemic -- pdm09 -- shows that the virus has passed from humans to swine ...

Flu A and flu B are two different strains of influenza, explains Thomas Russo, M.D., professor and chief of infectious ...

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

Specifically, the CDC notes that H1N1- and H3N2-related variants, both type A flu strains, are the predominant flu viruses circulating this season. But what does it mean to have a flu A or flu B ...