One undocumented immigrant child being housed on an air force base on the U.S.-Mexico border has been diagnosed and hospitalized with H1N1, or swine flu. According to the CDC, it's unlikely for children traveling to the U.S. from Central America to have influenza, and it is not a recommended vaccine. The H1N1 virus sparked a pandemic in 2009, and has continued to circulate after the WHO declared it over in August 2010.