Friday, December 01, 2017

FluView Week 47: Influenza Increases Across The United States


With the important caveat that the CDC's numbers are looking back a couple of weeks -  and by now flu is likely more widespread than the maps (above) would indicate - today's Fluview Report shows that influenza continues to rise, particularly in the southeastern United States and parts of the upper Midwest.

As we saw earlier today with both Japan and South Korea (see South Korean CDC Issues Early Influenza Warning) this year's flu season appears to be starting fairly early.  Based on the percentage of outpatient visits for ILI reported by ILNet (see below), flu this year appears to be rising earlier than any year since the 2009 pandemic.

The P&I (pneumonia & influenza) mortality rate (below) remains under the epidemic threshold, although these numbers lag two weeks behind the rest (Nov 11th), and P&I mortality is notoriously a trailing indicator. 

All of which suggests that if you've been waiting for flu season to pick up before getting that flu shot, you need to be getting one now, since it takes about 2 weeks for full immunity to kick in.

Some additional excerpts from today's report include:
2017-2018 Influenza Season Week 47 ending November 25, 2017

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

During week 47 (November 19-25, 2017), influenza activity increased in the United States.

  • Viral Surveillance: The most frequently identified influenza virus type reported by public health laboratories during week 47 was influenza A. The percentage of respiratory specimens testing positive for influenza in clinical laboratories is increasing.
  • Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below the system-specific epidemic threshold in the National Center for Health Statistics (NCHS) Mortality Surveillance System.
  • Influenza-associated Pediatric Deaths: No influenza-associated pediatric deaths were reported.
  • Influenza-associated Hospitalizations: A cumulative rate of 2.0 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported.
  • Outpatient Illness Surveillance:The proportion of outpatient visits for influenza-like illness (ILI) was 2.3%, which is above the national baseline of 2.2%. Regions 1, 4, 6 and 7 reported ILI at or above region-specific baseline levels. Three states experienced high ILI activity; one state experienced moderate ILI activity; 10 states experienced low ILI activity; the District of Columbia, New York City and 36 states experienced minimal ILI activity; and Puerto Rico had insufficient data.
  • Geographic Spread of Influenza:The geographic spread of influenza in four states was reported as widespread; Guam and 10 states reported regional activity; Puerto Rico and 24 states reported local activity; and the District of Columbia, the U.S. Virgin Islands and 12 states reported sporadic activity

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