January 07, 2014|Categories: Analytics and Research
In this report, from our third consecutive week monitoring this season’s flu outbreak, the athenaResearch team tracks trends as the recent CDC summary of flu activity (week ending December 28) reports a continued increase in flu diagnoses, particularly with H1N1. You might know the H1N1 strain best by the name “swine flu,” a virus that reached pandemic status in 2009-2010, and is now receiving increased attention in the media. (See more on the CDC report here.)
Despite that reported increase, the first week of 2014 shows an interruption, at the national level, from steep climbs in preceding weeks. Figure 1 shows that rates1 for Week 1 of 2014 are slightly lower than those for Week 52 of 2013.
It’s worth noting that the flu rate for the last two weeks of 2013 may be slightly overstated; because those were holiday weeks, patients may have been more likely to visit their doctor for acute issues (such as flu systems) rather than routine appointments.
Our athenaResearch team believes this decline in the first week of 2014 may only be temporary, as flu diagnoses are now widespread across the United States for the first time this season, for the two weeks ending on January 6, 2014 (see Figure 2).
It’s difficult to determine whether levels are at, or near, this season’s peak, as previous seasons have exhibited “double peaks,” where the flu spikes twice throughout the season.
When we break out flu rates by key regions (as shown in Figure 3), as we did in last week’s athenaResearch flu report, we can see that a drop in the South drove this week’s national decline.
The Middle Atlantic, New England and Pacific regions of the country did show flu rate increases this past week, though at much lower trajectories than the recent spike experienced in the South. Hopefully, we will continue to see rates decline or, at least, find no sharp rises across regions. In the meantime, we will use weekly updates to report any noteworthy trends that we find.
Acknowledgement: athenaResearch would like to thank John Brownstein, PhD, Associate Professor at Harvard Medical School, and Edward Goldstein, PhD, Senior Scientist at Harvard School of Public Health, for their advice on the interpretation of our flu data.
1 Data is based on claims created for physician encounters. Since claims may not be created until several days after time of service, data for the most recent reporting week (service dates ending on Saturdays) will not include claims created after the report creation date (midnight Sunday).
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