The state that has the most flu outbreaks varies year by year, with Oklahoma having the highest influenza rate during the 2014 flu season, according to Walgreens, and Nevada being hardest hit in 2013, according to Gallup. Walgreens used data from retail prescriptions, and Gallup used data from telephone surveys. Other states with high flu activity in 2014 included Texas, Mississippi and Tennessee, indicates Walgreens.
In 2013, on any given day, 2.9 percent of Nevada residents reported being sick with the flu. California was not far behind, with 2.6 percent of residents reporting flu symptoms, and New York followed with 2.5 percent.
There are multiple strains of influenza, including the virus known as H3N2v or "swine influenza." Indiana had the most cases of H3N2v during the period between August 2011 and July 2015, according to the Centers for Disease Control and Prevention. Ohio had the second largest number of cases.