For the first time in more than two months, red is no longer the dominant color on the CDC's ILI (influenza-like-illness) activity map, as more states report a drop in flu activity across the country.
While outpatient visits for ILI have declined for the third week running, at 3.7% it continues above the national baseline of 2.2%, suggesting this year's flu season as at least a few more weeks to run.
This year's record number of flu-related hospitalizations continues rise, with the overall rate reaching 86.7 per 100,000 population. Those over 65 are the hardest hit (370.6 per 100,000 population), followed by adults aged 50-64 (93.6 per 100,000 population) and children aged 0-4 years (62.5 per 100,000 population).
While overall flu has declined, influenza B continues to gain ground this week, now making up more than half (52.9%) of viruses sub-typed by the CDC.
Lastly the CDC reports another 5 pediatric flu-related deaths, which is a sharp decline over the past couple of weeks, making a total of 119 influenza-associated pediatric deaths reported for the 2017-2018 season. As reporting is often delayed by several weeks, this number is likely to rise over the next month or so.
Some excerpts from the summary of today's FluView report follow:
All data are preliminary and may change as more reports are received.
Synopsis:During week 9 (February 25-March 3, 2018), influenza activity decreased in the United States.
- Viral Surveillance: Overall, influenza A(H3) viruses have predominated this season. However, in recent weeks the proportion of influenza A viruses has declined, and during week 9, the numbers of influenza A and influenza B viruses reported were similar. The percentage of respiratory specimens testing positive for influenza in clinical laboratories decreased.
- Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was above the system-specific epidemic threshold in the National Center for Health Statistics (NCHS) Mortality Surveillance System.
- Influenza-associated Pediatric Deaths: Five influenza-associated pediatric deaths were reported.
- Influenza-associated Hospitalizations: A cumulative rate of 86.3 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 3.7%, which is above the national baseline of 2.2%. All 10 regions reported ILI at or above region-specific baseline levels. New York City and 21 states experienced high ILI activity; 15 states experienced moderate ILI activity; the District of Columbia, Puerto Rico, and five states experienced low ILI activity; and nine states experienced minimal ILI activity.
- Geographic Spread of Influenza:The geographic spread of influenza in Puerto Rico and 34 states was reported as widespread; Guam and 12 states reported regional activity; the District of Columbia and four states reported local activity; and the U.S. Virgin Islands reported no activity.