During the week of Feb. 20 to Feb. 26, 2,106 of 7,543 specimens tested
by WHO and the National Respiratory and Enteric Virus Surveillance System were
positive for influenza, bringing the total number of influenza cases to 36,824
since Oct. 3, according to the CDC’s weekly report.
In week 8 of the 2011
influenza surveillance period, influenza A accounted
for 74% of the influenza cases, and influenza B accounted for 26%. Among the
influenza A cases, 32.4% of these were subtyped as influenza A (H3) and 23.1%
were subtyped as influenza A (2009 H1N1). The remaining cases were not
subtyped.
There were 14 influenza-associated pediatric deaths reported during week
8: four deaths were associated with a non-subtyped influenza A virus, two
deaths were associated with influenza A (H3), four were associated with a 2009
influenza A (H1N1) virus, and four deaths were associated with
influenza B virus. Fifty-five total pediatric deaths
have been reported during the 2010-2011 season. The proportion of deaths
attributed to pneumonia and influenza overall during week 8 was 8%, and this is
the fifth consecutive week that pneumonia and influenza mortality has been at
or more than epidemic threshold.
The proportion of outpatient visits for influenza-like illness during
week 8 was 4%, which is more than the national baseline of 2.5%. All 10 regions
reported influenza-like illnesses (ILI) at or more than the region-specific
baseline level. Eighteen states reported high ILI activity; 16 states and New
York City experienced low ILI activity; 10 states experienced minimal ILI
activity; six states experienced moderate ILI activity. The District of
Columbia had insufficient data.