Regional %ILI Generally Improving

[JimO]

Source: http://www.cdc.gov/flu/weekly/regions2008-2009/hhssenusmap.htm

The %ILI in most of the 10 regions in the U.S. have either leveled off or are beginning to decrease, which is odd to me given the number of reports of school absences, community outbreaks, reports of ERs having to set up separate triage areas, and the fact that we are just beginning the flu season.

It is good news, for sure, assuming the %ILI is still a reliable indicator and that infections are actually decreasing. However, I wonder if there are fewer ED or doctor office visits given all the publicity about staying home unless there are serious complications, but not necessarily fewer infections. Otherwise, either there is a lag between current reports of illness and data getting to the CDC from sentinal providers, or there has been a lessoning of the pandemic in the U.S.

I'd also like to see if the number of sentinal providers reporting has gone down. If those who are overwhelmed with patients don't have time to collect the data and send it to the CDC, then this too could make the %ILI data that is reported biased to indicate fewer infections.

Any thoughts?

 

[Ronan Kelly]

Re: Regional %ILI Generally Improving

From New Jersey,
It seems like a tiny fraction are actually reporting. Has to leave a larger degreee of uncertainty in any calculations.


Sentinel Provider Surveillance
During week 38, 04.15% of sentinel provider patient visits were due to ILI. These data reflect reports
from nine (18%) of the enrolled sentinel providers.
During week 37, 2.75% of sentinel provider patient visits were due to ILI. These data reflect reports from
eighteen (36%) of the enrolled sentinel providers.

http://www.state.nj.us/health/flu/documents/stats08/flummwr_38.pdf

 

[Laidback Al]

Re: Regional %ILI Generally Improving

JimO, your hypothesis about overworked sentinel providers behind in reporting remains a possibility.

I wouldn't put much stock in minor fluctuations - we should expect some random fluctuations on a week to week basis. In almost all of the charts for all regions, the %ILI case is substantially above the baseline. Because we are barely into the next flu season with the %ILI already way above the baseline, I think we will see it go higher in the coming weeks. For me, the long term trend is still up.