Flu cases have been on the rise since the beginning of the year throughout North Texas, the state and the United States. The Texas Department of State Health Services is categorizing current statewide flu activity as “widespread,” and data indicates that flu levels are the highest yet this season as of the last reporting period, which ended Feb. 4. Flu season runs from October through May. Aisha Souri, epidemiologist for Collin County Health Services, said the Type A (H3) flu virus is the most frequently identified this year. Type A and Type B flu viruses display the same symptoms. The composition of the U.S. flu vaccine is reviewed each year and recommendations are made to match circulating flu viruses. CDC officials said the flu vaccine is not a perfect tool, but is the best way to protect against flu infection. The CDC recommends people age 6 months and older get a flu shot by the end of October every year, but receiving one later may still be effective, Souri said. Graphic sources: Collin County, Denton County, Tarrant County, Texas Department of State Health Services, Centers for Disease Control and Prevention. Flu case numbers reflect the cases reported by public health laboratories only. Note: Flu statistics for Jan. 29-Feb. 4 were not yet available from Tarrant County. Denton County officials said the county does not track the school absenteeism rate.