(CNN) — The United States has officially surpassed the “epidemic” threshold with this season’s flu virus, according to the latest data from the Centers for Disease Control and Prevention.
The CDC estimates that nearly 7% of all deaths nationwide were due to pneumonia and influenza during the week ending December 20 — the last week for which the agency has compiled figures on the outbreak.
Influenza is now “widespread” in 36 states, the agency said Tuesday.
Nationwide, a total of 15 children have died so far this flu season, including one in the third week of December.
Flu-related hospitalizations among people 65 years and older has reached 38.3 per 100,000 people, the highest rate of any age group.
The CDC recommends vaccination for everyone 6 months of age and older, for as long as the flu virus is circulating. The agency has warned, however, that this year’s flu strain has mutated in ways that make the vaccine less effective than experts initially hoped.
Researchers say the timing of flu season is difficult to anticipate, but flu activity generally peaks in the U.S. between December and February, and seasonal flu activity can persist as late as May.