The Walgreens Flu Index provides state- and market-specific information on flu activity. The index is compiled using retail prescription data for antiviral medications used to treat flu across Walgreens locations nationwide. Activity measured covered the November 2014 to February 2015 time period.

After Oklahoma, Arkansas and Mississippi, rounding out the top 10 states with the most flu activity this season were Texas, Tennessee, Louisiana, Alabama, Kentucky, Nebraska and South Carolina.

The top 10 markets for flu activity over the November-to-February time period, according to designated market area (DMA), were Oklahoma City; Harlingen-Weslaco-Brownsville-McAllen, Texas; Dallas-Fort Worth, Texas; Jackson, Miss.; Fort Smith-Fayetteville, Ark.; Knoxville, Tenn.; Austin, Texas; Little Rock-Pine Bluff, Ark.; Chattanooga, Tenn.; and Tulsa, Okla.

“In just its first season, the Flu Index quickly became a resource that people — and news media in particular — came to rely upon, and strong awareness helped deliver a call to action that had a positive impact on flu immunization rates,” Richard Ashworth, president of pharmacy and retail operations at Walgreens, said in a statement. “This is another way in which we’re helping to better the health of our communities by providing the preventive health information and services they need.”

Meanwhile, the top 10 markets with the least flu activity this season were Portland, Ore.; Hartford-New Haven, Conn.; Boston; Fresno-Visalia, Calif.; Sacramento, Calif.; Tucson, Ariz.; Buffalo, N.Y.; Providence, R.I.; Seattle-Tacoma, Wash.; and Los Angeles.

Walgreens noted that the Flu Index is designed to indicate which populations are experiencing the highest incidence of flu, not to show levels or severity of flu activity.