Flu activity indicators that rose early this season are beginning to show declines, but indicators that reflect severity are rising, according to the latest FluView report from the Centers for Disease Control and Prevention.
The CDC noted that severity indicators typically lag a few weeks behind early activity indicators. Seasons in which H3N2 viruses are predominant tend to be associated with greater severity in terms of hospitalizations and deaths.
CDC Director Thomas Frieden, MD, MPH, said the nation is about halfway through what he called a “worse than average” flu season.
For the week of Jan. 6-12, the proportion of people seeing their healthcare provider for influenza-like illness decreased to 4.6% from 4.8% the previous week. The level remained above the national baseline for the sixth consecutive week.
Thirty states and New York City reported high ILI activity, an increase from 24 states last week. Additionally, 10 states reported moderate levels of ILI activity. States reporting high ILI activity for the week of Jan. 6-12 include Alabama, Arkansas, Colorado, Connecticut, Delaware, Georgia, Idaho, Illinois, Indiana, Kansas, Louisiana, Maryland, Michigan, Mississippi, Missouri, Nebraska, New Hampshire, New Jersey, New York, North Carolina, North Dakota, Oklahoma, Pennsylvania, Rhode Island, Tennessee, Texas, Utah, Vermont, Virginia and Wyoming.
A total of 48 states, up from 47 the previous week, reported widespread geographic influenza activity. “Particularly for people out West, you probably have most of the flu season still to come,” Frieden said.
Frieden said flu vaccination doses should be available to anyone who wants one, although a little shopping around may be required. “There are more vaccines out there for providers to order,” he said.
Since Oct. 1, 5,249 laboratory-confirmed influenza-associated hospitalizations have been reported, marking an increase of 1,539 hospitalizations from the previous week. This translates to a rate of 18.8 influenza-associated hospitalizations per 100,000 people in the United States.
Influenza-associated hospitalization rates continue to be highest among people 65 and older. Of the influenza-associated hospitalizations that have been reported this season, 49.6% have been among that age group. It has been “a bad year for the elderly,” Frieden said. (Hospitalization data are collected from 15 states to calculate a rate of laboratory-confirmed influenza-associated hospitalizations that is reasonably representative of the nation. These data do not reflect the actual total number of influenza-associated hospitalizations in the United States.)
The proportion of deaths attributed to pneumonia and influenza based on the 122 Cities Mortality Reporting System increased sharply and remained above the epidemic threshold for the second consecutive week.
Nine influenza-related pediatric deaths were reported during the week of Jan. 6-12. Two of the deaths were associated with an influenza A (H3) virus, four were associated with an influenza A virus of unknown subtype and three were associated with an influenza B virus. This brings the total number of influenza-associated pediatric deaths reported to the CDC for 2012-13 to 29.
For people who get the flu, the CDC has said, antiviral drugs can be effective at limiting the duration and severity. “We expect to see a lot more cases, followed by complications of the flu and deaths,” Frieden said. “Thats why were emphasizing prompt treatment.”
For more data, see www.cdc.gov/flu/weekly/.