2009 swine flu pandemic 2009 swine flu pandemic the 2009 swine flu pandemic, caused by the h1n1/swine flu/ influenza virus and declared by the world health organization (who) from june 2009 to august 2010, is the third recent flu pandemic involving the h1n1 virus (the first being the 1918–1920 spanish flu pandemic and the second being the 1977 russian flu). the first two cases were discovered independently in the united states in april 2009. the virus appeared to be a new strain of h1n1 that resulted from a previous triple reassortment of bird, swine, and human flu viruses which further combined with a eurasian pig flu virus, leading to the term "swine flu". 2009 swine flu pandemic 50,000+ confirmed cases 5,000–49,999 confirmed cases 500–4,999 confirmed cases 50–499 confirmed cases 5–49 confirmed cases 1–4 confirmed cases no confirmed casesdiseaseinfluenzavirus strainpandemic h1n1/09 virussourcepigs, likely indirectlylocationworldwidefirst outbreaknorth americaindex caseveracruz, mexicoarrival dateseptember 2008datejanuary 2009 – 10 august 2010confirmed cases491,382 (lab-confirmed)suspected cases‡700 million to 1.4 billion (estimate)deathslab confirmed deaths: 18,449 (reported to the who)estimated excess death: 284,000‡suspected cases have not been confirmed by laboratory tests as being due to this strain, although some other strains may have been ruled out. influenza (flu) types avian a/h5n1 subtype canine equine swine a/h1n1 subtype vaccines 2009 pandemic pandemrix live attenuated seasonal flu vaccine brands treatment amantadine baloxavir marboxil laninamivir oseltamivir peramivir rimantadine umifenovir zanamivir pandemics 1889-1890 russian flu 1918 spanish flu 1957-1958 asian flu 1968 hong kong flu 1977 russian flu 2009 swine flu outbreaks 1976 swine flu 2006 h5n1 india 2007 australian equine 2007 bernard matthews h5n1 2008 west bengal 2015 united states h5n2 outbreak 2020–2022 h5n8 outbreak