US flu markers continued their slow slide toward spring last week, though there were a few hot spots, especially Hawaii and Texas, where clinic visits for flulike illness are running much higher than average, the US Centers for Disease Control and Prevention (CDC) said it its latest update today.
For the nation as a whole, however, the level of doctor's visits for flulike illness for the second week in a row remained at the national baseline of 2%, while another closely watched gauge—the percentage of respiratory specimens testing positive for flu—dropped last week from 8.7% to 8.4%.
Though the 2009 H1N1 virus remained the dominant strain, the percentage of influenza B specimens detected by labs increased last week from 20% to 32.3%. Health officials have said it's not unusual to see late-season increases in influenza B activity.
Testing programs to monitor antiviral resistance identified six more samples that showed resistance to oseltamivir (Tamiflu), raising the season's total to 40. So far none of the seasonal flu viruses tested has shown resistance to the zanamivir (Relenza), the other approved antiviral drug.
Regarding flu hospitalizations, the CDC said 7,910 lab-confirmed ones have been reported so far this season, for a cumulative rate of 29.2 per 100,000 people. That figure is lower than the 40.2 per 100,000 level seen at this point last season, when the H3N2 virus was dominant.
This is the first season since the pandemic year that the 2009 H1N1 virus has been the dominant strain, and while the number of deaths hasn't been unusual, larger percentages have been seen in some children and younger-to-middle aged adults, similar to a pattern seen during the pandemic.
Also seeing a drop last week was the overall percentage of deaths from pneumonia and flu, which tumbled from 7.9% to 6.9%, putting it below the epidemic threshold for the first time in 8 weeks, according to the CDC.
Three more pediatric flu deaths were reported, nudging the season's total to 68. Two were associated with the 2009 H1N1 virus and occurred earlier in the flu season, and one was linked to an unsubtyped influenza A virus, which occurred in the week ending Feb 1.
Only four states reported widespread geographic flu activity, down from eight the week before. All four of the states are in the Northeast: Connecticut, Delaware, Massachusetts, and New York.
Activity in Europe varies
In the European region, flu activity continued to vary, with Greece the only country to report high-intensity activity, the European Centre for Disease Prevention and Control (ECDC) said today.
Twelve countries are reporting widespread geographic flu activity, and six reported increasing flu trends: Austria, Croatia, Estonia, the Netherlands, Romania, and Northern Ireland.
The percentage of respiratory specimens that were positive for flu in Europe last week was 32%, a decline from the previous week. The dominant strain has varied by country, with some reporting mainly H3N2 while others are finding a larger portion of 2009 H1N1.
See also:
Mar 14 CDC FluView report
Mar 14 CDC flu situation update
Mar 14 ECDC weekly flu surveillance report
