The Asian Flu was a pandemic outbreak of influenza that originated in China in 1957 and spread worldwide (including to the United States of America) that same year. The virus lasted until 1958.

The Asian Flu was the H2N2 strain (a notation that refers to the configuration of the hemagglutinin and neuraminidase proteins in the virus) of type A influenza, and a flu vaccine was developed in 1957 to contain its outbreak. Worldwide it is estimated that at least one million people died from this virus; in the United States the death toll was comparatively mild, numbering approximately 72,000 people.

The Asian Flu strain later evolved via antigenic shift into H3N2, the so-called Hong Kong Flu which caused a milder pandemic from 1968 to 1969.

From October 2004 to February 2005, some 3700 test kits of the 1957 virus were spread around the world from College of American Pathologists (CAP). Most kits containing the flu are not taken as seriously as were a serious virus and thus escaped in a High-Containment laboratory in Canada. CAP assists laboratories in accuracy by providing unidentified samples of viruses; private contractor Meridian Bioscience in Cincinnati, US chose the 1957 strand instead of one of the newer Influenza A strands. The flu is considered deadly and the US government called for the vials containing the strain to be destroyed. [1]