Dec. 13 (UPI) -- More than 4,000 new cases of influenza were confirmed across the country this week as flu season shifts into high gear.
Additionally, the CDC estimates that so far this season there have been at least 2.6 million illnesses, 23,000 hospitalizations and 1,300 deaths from flu.
According to results posted in the U.S. Centers for Disease Control and Prevention's weekly FluView report, the new cases bring the total of laboratory-confirmed influenza diagnoses for the season to close to 20,000. In all, Puerto Rico and 11 states -- Alabama, Arkansas, Georgia, Mississippi, Nebraska, New Mexico, South Carolina, Tennessee, Texas, Virginia and Washington -- reported high flu activity during the most recent period covered in the report, which ended Saturday.
Arkansas is new to that list, while Minnesota and Nevada reported "moderate" flu activity this week, after reporting high activity the prior week.
The CDC reported that 11.3 percent of all clinical laboratory tests for the virus during the week ending Saturday were positive, up from 10.2 percent the previous week.
Overall, 3.2 percent of all visits to healthcare providers across the country that week were related to influenza, down from 3.5 percent the previous week.
Nearly 13,000 people across the country were hospitalized for flu-related causes, up from less than 9,000 the week prior. Five percent of all deaths in the United States during that week were caused by either pneumonia or influenza.
This latter figure remains below the CDC's established threshold for an epidemic of 6.5 percent. To date, 10 children in the country have died from influenza, with four new deaths documented since the last report.
Antiviral medications are an important adjunct to flu vaccine in the control of influenza, the agency noted, adding that more than 99 percent of the influenza viruses tested this season are susceptible to the four FDA-approved influenza antiviral medications recommended for use in the United States.