The weekly flu report by the Centers for Disease Control and Prevention said flu activity was widespread in at least 35 states -- up from 25 the week before. Widespread flu activity means half of a state's counties report flu activity.
Of the 9,482 specimens tested and reported by U.S. World Health Organization and National Respiratory and Enteric Virus Surveillance System collaborating laboratories 2,486, or 26.2 percent were positive for influenza -- compared with 6,419 specimens, 1,711, or 27 percent, positive for influenza the week before.
Four influenza-associated pediatric deaths were reported. Three deaths were associated with a 2009 H1N1 virus and occurred during the week ending Dec. 28, 2013, and one ending the week of Jan. 4.
Adult flu deaths are not monitored by the CDC, but media reports said there were so many flu hospitalizations in the Dallas-Forth Worth area and San Francisco Bay area, overflow tents had to be set up to accommodate flu patients, CNN reported.
Other areas reported restrictions in hospital and nursing home visits. For example, Fairview Health Services is restricting visitors to its six Minnesota hospitals to reduce the spread of influenza, a sign that the virus is spreading, the Star Tribune in Minneapolis reported. The restrictions will last for the rest of the winter, hospital officials said.
However, flu intensity -- measured by the amount of outpatient visits to healthcare providers for influenza-like illnesses -- stayed the same from the previous week, at 20 states.
Alabama, Arkansas, Colorado, Idaho, Illinois, Indiana, Kansas, Kentucky, Louisiana, Minnesota, Mississippi, Missouri, Nevada, New Mexico, North Carolina, Oklahoma, Oregon, Tennessee, Texas and Virginia reported high high influenza-like illnesses.
New York City, Alaska, California, New Jersey, Pennsylvania, South Carolina, South Dakota and Utah reported moderate influenza-like illnesses. Delaware, Florida, Georgia, Massachusetts, Michigan, Montana, Ohio, Washington, West Virginia, Wisconsin and Wyoming experienced low influenza-like illnesses.
Twelve states experienced minimal influenza-like illnesses: Arizona, Connecticut, Hawaii, Iowa, Maine, Maryland, Nebraska, New Hampshire, New York, North Dakota, Rhode Island and Vermont.
Data were insufficient to calculate flu activity in the District of Columbia.