# 4984
The CDC’s FluView report has been on hiatus over the summer, as influenza activity is generally too low to warrant constant surveillance (last summer, when novel H1N1 erupted, was an exception).
It is early fall again in the Northern hemisphere; schools are back in session, the sun’s rays are less direct, temps and the humidity are dropping, and seasonal influenza is beginning to make its yearly appearance.
So every week, through the end of flu season next May, we will get a detailed (early) look at the latest influenza numbers via the CDC’s FLUVIEW report.
I only post a few highlights each week. Follow the link to read the entire report, or visit the CDC’s Flu Activity & Surveillance page to access the archive of older weekly reports going back a decade.
While flu activity remains low, the report indicates it is starting to rise – and perhaps most significantly (and as we’ve been anticipating over the summer) – the H3N2 virus appears to account for a significant portion of the influenza strains being identified.
2010-2011 Influenza Season Week 40 ending October 9, 2010
All data are preliminary and may change as more reports are received.
Synopsis:
Influenza A (H3N2), 2009 influenza A (H1N1), and influenza B viruses co-circulated at low levels in the United States during the summer months. During week 40 (October 3-9, 2010), influenza activity was low in the U.S.
- Forty-five (3.3%) 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.
- The proportion of deaths attributed to pneumonia and influenza (P&I) was below the epidemic threshold.
- No influenza-associated pediatric deaths were reported.
- The proportion of outpatient visits for influenza-like illness (ILI) was below the national baseline. All 10 regions reported ILI below region-specific baseline levels and all 48 states with sufficient data experienced minimal ILI activity.
- Geographic spread of influenza in the District of Columbia, Guam, Puerto Rico, and 19 states was assessed as sporadic, 31 states reported no influenza activity and the U.S. Virgin Islands did not report.
U.S. Virologic Surveillance:
WHO and NREVSS collaborating laboratories, located in all 50 states and Washington, D.C., report to CDC the number of respiratory specimens tested for influenza and the number positive by influenza type and subtype. The results of tests performed during the current week are summarized in the table below.
Pneumonia and Influenza (P&I) Mortality Surveillance
During week 40, 6.5% of all deaths reported through the 122-Cities Mortality Reporting System were due to P&I. This percentage was below the epidemic threshold of 6.6% for week 40.
ILINet State Activity Indicator Map:
Data collected in ILINet are used to produce a measure of ILI activity* by state. Activity levels are based on the percent of outpatient visits in a state due to ILI and are compared to the average percent of ILI visits that occur during spring and fall weeks with little or no influenza virus circulation.
Over the summer the CDC antigenically analyzed 63 influenza isolates (23 novel H1N1, 24 H3N2, 16 influenza B) and determined that:
- (95.7%) of the H1N1 viruses tested were closely related to the H1N1 (A/California/7/2009-like) component of this year’s flu shot.
- (91.7%) of the H3N2 viruses tested were closely related to the H3N2 (A/Perth/16/2009-like) component of this year’s flu shot.
- (75%) of the influenza B viruses tested were closely related to the B/Brisbane/60/2008-like strain component of this year’s flu shot.
All in all, a pretty good sign that this year’s flu shot ought to be effective against the majority of influenza viruses currently in circulation.
