H1N1 Flu: Situation Update: February 19, 2010

Washington, DC–(ENEWSPF)– FluView reports that for the week of February 7 – February 13, 2010, flu activity in the United States was relatively low, with most flu continuing to be caused by 2009 H1N1. Flu activity, caused by either 2009 H1N1 or seasonal flu viruses, may rise and fall, but is expected to continue for weeks. It’s possible that the United States could experience another wave of flu activity, or more likely, localized outbreaks of 2009 H1N1 in communities that have been relatively unaffected by illness thus far, or where 2009 H1N1 vaccination rates may have been lower.

Each week CDC analyzes information about influenza disease activity in the United States and publishes findings of key flu indicators in a report called FluView. During the week of February 7 – February 13, 2010, most key flu indicators remained about the same as during the previous week. Below is a summary of the most recent key indicators:

  • Visits to doctors for influenza-like illness (ILI) nationally increased slightly this week over last week, but are still low for this time of year. The national increase in ILI was driven by elevated ILI in regions 4, 7, and 9. Region 4 is comprised of Alabama, Florida, Georgia, Kentucky, Mississippi, North Carolina, South Carolina and Tennessee. Region 7 is comprised of Iowa, Kansas, Missouri and Nebraska, and region 9 is comprised of Arizona, California, Hawaii and Nevada
  • Laboratory-confirmed hospitalizations rates have leveled off and very few hospitalizations were reported by states during the week ending February 13.
  • The proportion of deaths attributed to pneumonia and influenza (P&I) based on the 122 Cities Report increased slightly over the previous week but remains lower than expected for this time of year. In addition, another two flu-related pediatric deaths were reported this week: both deaths were associated with laboratory-confirmed 2009 H1N1. Since April 2009, CDC has received reports of 326 laboratory-confirmed pediatric deaths: 277 due to 2009 H1N1, 47 pediatric deaths that were laboratory confirmed as influenza, but the flu virus subtype was not determined, and two pediatric deaths that were associated with seasonal influenza viruses. (Laboratory-confirmed deaths are thought to represent an undercount of the actual number. CDC has provided estimates about the number of 2009 H1N1 cases and related hospitalizations and deaths.
  • No states reported widespread influenza activity. Three states reported regional influenza activity. They are: Alabama, Georgia and South Carolina.
  • Almost all of the influenza viruses identified so far continue to be 2009 H1N1 influenza A viruses. These viruses remain similar to the virus chosen for the 2009 H1N1 vaccine, and remain susceptible to the antiviral drugs oseltamivir and zanamivir with rare exception.

*All data are preliminary and may change as more reports are received.

During week 6 (February 7-13, 2010), influenza activity remained at approximately the same levels as last week in the U.S.

  • 129 (3.5%) specimens tested by U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories and reported to CDC/Influenza Division were positive for influenza.
  • All subtyped influenza A viruses reported to CDC were 2009 influenza A (H1N1) viruses.
  • The proportion of deaths attributed to pneumonia and influenza (P&I) was below the epidemic threshold.
  • Two influenza-associated pediatric deaths were reported. Both deaths were associated with 2009 influenza A (H1N1) virus infection.
  • The proportion of outpatient visits for influenza-like illness (ILI) was 2.1% which is below the national baseline of 2.3%. Three of 10 regions (Regions 4, 7, and 9) reported ILI above region-specific baseline levels.
  • No states reported widespread influenza activity, three states reported regional influenza activity, Puerto Rico and nine states reported local influenza activity, the District of Columbia and 35 states reported sporadic influenza activity, the U.S. Virgin Islands and three states reported no influenza activity, and Guam did not report.

Source: CDC.GOV