Flu is widespread in 43 U.S. states, up from 36 states in the prior week, the U.S. Centers for Disease Control and Prevention reported on Monday.
Six children died from the flu during the last full week in December, bringing the total flu deaths to 21 this season, the report showed.
Last week the CDC reported for the first time that deaths from flu and pneumonia reached an epidemic level, comprising 6.8 percent of all deaths. That figure slipped slightly below the epidemic level in this week's report, the CDC said.