WASHINGTON, Jan. 10 (Xinhua) -- The number of U.S. states with widespread flu infections increased from 25 to 35 last week, said the U.S. Centers for Disease Control and Prevention (CDC) Friday.
The predominant circulating strain so far this season is the H1N1 virus, which caused a worldwide pandemic in 2009, the CDC said in its weekly flu report. "Widespread" means flu activity occurs in at least half of the regions in a U.S. state.
This season's flu has yet to be declared an "epidemic," as the 6.9 percent of deaths for the week of December 29,2013 to January 4, 2014, which were blamed for pneumonia and influenza, was below the epidemic threshold of 7.1 percent, according to the CDC.
Four influenza-associated pediatric deaths were reported during the week and altogether 10 influenza-associated pediatric deaths were reported for this season. During last year's severe flu season, 171 children died.
Flu activity most commonly peaks in the United States in January or February. Seasonal flu activity, however, can begin as early as October and continue to occur as late as May, according to the CDC.