U.S. Flu Forecasts --- 2009 Week 37 (Produced 16 September)

Regional Influenza Activity for week 37 (ending 19 September)

2009 Week 37 (nowcast)


Color coding is based on region-specific baselines.
Green and yellow: below baseline; orange: between baseline and 1.5 times baseline;
red: above 1.5 times baseline; dark red: above 3 times baseline; very dark red: above 6 times baseline.

1 Summary for week 37 (ending 19 September)

2 Current Influenza Activity

3 Expected Influenza Activity

Historically, there tends to be a fairly slow increase in ILI% until Thanksgiving Day. The Thanksgiving holidays are associated with an additional increase of 15%. It is clear that this season is already developing in a very different way.

4 Flu Season Forecasts of Influenza Activity

The dynamic model M2 describes normal flu seasons quite well, but is inappropriate during pandemic flu. For that reason, scenarios are reported.

The one-year ahead forecasts use the average nowcasts for week 36 and 37 as the starting point for forecasting. Then three assumptions are used to capture pandemic flu activity:

Note that the dynamics in the model effectuates a moderating effect after a longer period of very rapid increase. If these assumptions hold, very high levels of ILI% should be expected.

5 References and links

6 Archive


The results reported here are based on forecast, and are therefore uncertain. These results are my personal opinion, based on extensive modeling, and not endorsed by either the CDC or Google.

Jurgen A. Doornik, University of Oxford, UK