The number of U.S. states reporting widespread flu activity jumped from 23 to 36 last week, the U.S. Centers for Disease Control and Prevention (CDC) said Friday.
"Seasonal influenza activity increased sharply in the United States," the CDC said in a report covering the week ending Dec. 23. "H3N2 viruses continue to predominate."
According to the CDC, widespread influenza activity was reported in Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Florida, Georgia, Idaho, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Mexico, New York, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, South Dakota, Texas, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.
"Widespread" means that more than 50 percent of geographic regions within a U.S. state are reporting flu activity.
Since Oct. 1, 2,485 laboratory-confirmed influenza-associated hospitalizations have been reported, translating to a cumulative overall rate of 8.7 hospitalizations per 100,000 people in the United States, the CDC said.
The proportion of deaths attributed to pneumonia and influenza was two percent for the week ending Dec. 9, below the epidemic threshold of 6.8 percent for that week, said the CDC.
In addition, a total of 12 influenza-associated pediatric deaths for the 2017-2018 season have been reported.
The CDC recommended the use of antiviral drugs as early as possible to treat flu illness in people who are very sick with flu and those at high risk of serious flu complications.
"While flu vaccination is still recommended for people who have not yet gotten vaccinated, antiviral drugs are an important second line of defense that can be used to treat flu illness," the U.S. agency added.