In March and April 2009, an outbreak of a new strain of influenza commonly referred to as "swine flu" infected many people in Mexico and other parts of the world, causing illness ranging from mild to severe.
The World Health Organization (WHO) and the U.S. Centers for Disease Control and Prevention (CDC)[6] expressed serious concerns that the new strain, which transmits between humans and has had a relatively high mortality rate in the possible and confirmed Mexican cases, has the potential to become an influenza pandemic.
[17] The pandemic outbreak was first detected in the Federal District, where surveillance began picking up a surge in cases of influenza-like illness starting on March 18.
Hundreds of soldiers and police officers mobilized by the government have handed out six million surgical masks to citizens in and around Mexico City.
[32] Marcelo Ebrard, Mexico City's mayor, has also asked all night-life facilities operators to shut down their places for ten days to prevent further infections.
[33] Health Secretary José Ángel Córdova said on April 24 that schools will probably be suspended for at least the following week then, and that it will take around ten days to see the evolution of the virus' behavior, and to consider other measures thereafter.
[34] On April 25, President Felipe Calderón declared an emergency which granted him the power to suspend public events and order quarantines.
[38] On April 27, Health Secretary José Ángel Córdova announced that schools of all levels throughout the nation will be suspended until May 6 to prevent the spread of the flu.
[39] As part of a marketing strategy, a mascot for the outbreak was released in Mexico City on April 29 depicting a blue plush virus with black eyes in reference of H1N1; but it was discontinued two days later.[why?
[citation needed] The Mexican teams that qualified to the 2009 Copa Libertadores began to have problems related to the swine flu outbreak, specially the Guadalajara Chivas who travelled to Chile to play against Everton.