The rate of outpatient clinic visits for influenza-like illnesses (ILI) jumped from 2.9% to 3.5% in the past week, and flu-related pediatric deaths have reached six, according to the latest weekly flu report from the Centers for Disease Control and Prevention (CDC).
ILI well above baseline
The ILI rate has been above the national baseline of 2.4% for 4 weeks, with 9 of the 10 US regions reporting elevated activity. The percentage of respiratory specimens that tested positive for flu rose to 10.2%, up from 8.0% the week before.
"The 2019-2020 flu season is underway for most of the country, however some parts of the country are still seeing lower levels of flu activity," the CDC said. "Activity is being caused mostly by influenza B/Victoria viruses, which is unusual for this time of year."
The CDC also emphasized that flu activity is expected to remain elevated for weeks, and urged people to get the seasonal flu vaccine if they have not done so yet.
Influenza B dominates, tied to child's death
Of subtyped influenza lab specimens tested in the week ending on Nov 30, 71.1% were influenza B, and 28.9% were influenza A. Of the influenza B specimens, 97.1% were of the Victoria lineage. Among influenza A viruses, 79.2% were 2009 H1N1.
"Nationally, influenza B/Victoria viruses are the most commonly reported influenza viruses among children age 0-4 years (46% of reported viruses) and 5-24 years (60% of reported viruses), while A(H3N2) viruses are the most commonly reported influenza viruses among persons 65 years of age and older (54% of reported viruses)," the CDC said.
One more pediatric death has been reported, and it was associated with an influenza B infection. So far, officials have confirmed six pediatric flu deaths in the 2019-20 flu season.
The CDC said the overall hospitalization rate, 2.7 per 100,000 population, mimics previous seasons and is up from 2.0 per 100,000 the week before. Adults over the age of 65 have the highest rate of hospitalization (7.0 per 100,000), followed by children ages 0 through 4 years (4.6 per 100,000 population) and adults ages 50 to 64 (2.7 per 100,000 population).
Among 784 hospitalizations reported in the week ending on Nov 30, 57.5% were associated with influenza A, and 41.5% with influenza B.
As reported last week, flu activity remains heaviest in southern states, with widespread activity reported in Alabama, California, Connecticut, Georgia, Indiana, Louisiana, Massachusetts, Mississippi, Nevada, New Mexico, New York, Pennsylvania, South Carolina, Tennessee, Texas, and Virginia.
ILI activity is high in 12 states and Puerto Rico, up from 7 states and Puerto Rico the previous week.
Dec 6 CDC FluView