I have updated the percent positive chart, while it the season has started early, the activity seems to have peaked, and while the peak is a little higher than all the seasons except the pandemic years (2009 - 2010) it does not seem dramatically worse than previous seasons (I am not looking at mortality, just percent positive), and I am not an expert.
The CDC has great info and data relating to the flu, I have posted the links below throughout the blog.
Keep healthy and safe.
Previous post:
The flu season has begun and according to the CDC (various media outlets), it appears that it is off to a earlier start than usual and the strain around this year is said to be nastier than usual. I can't comment on the nastiness of the strain, I did not seek out that kind of data, but I can look at the data provided by the CDC on their website (http://gis.cdc.gov/grasp/fluview/fluportaldashboard.html) on the number of samples tested for the flu.
The data is easy to find, and easy to download, so I played with it a bit to see what the numbers were telling me. First I compared this seasons percent positive specimens (number of samples positive as a percentage of samples submitted) compared to that of last year. From 1998 to date, only two seasons (2004 - 2005, and 2010 - 2011) have had higher rates (the rest were practically zero) at this time of year with 2005 - 2006) having rates higher than the rest, but not quite as high as this season.
The 2010 flu season were not normal as the Pandemic flu strain was also circulating that year and the year before. If you look at all those years together, it is amazing how in sync the start and finish of the flu season is each year. Aside from a few years (which included the ones with the pandemic flu), the flu season seems to start and finish remarkably tightly.
On this graph the numbers on the outside represent the week of the year, the lines show percent positive. As you can see most show peak activity around weeks 5 - 6. The years of the pandemic flu (2009 and 2010). Here is another view of the same data.
It is hard to see but the 2009 year has three peaks, the first around the same as the other years peaking around week 6, the second peaking around week 24 and the last one going up at week 38, but finally peaking in the 2010 season at week 42. While that season was not as bad as initially predicted, it was much worse than any in since 1998 (at least in the US). In this graph (above) I am showing the percent positive for the same period each year, below I have spread it out so you are looking at the periodicity over time.
Looking at the different strains circulation and this time at number of cases, not percent positive it is really easy to see where the pandemic occurred and to see just how different that year was from any other, and to see that while it was not the catastrophe predicted, it was pretty bad if you compare it to other years. In the graph above the pink shaded line is the same data as in the graph above, it shows percent positive, the line bars are the different strains circulating and the number positive of each. Below is the same graph without the pandemic strain and the percent positive. It is easier to see the way the strains circulate looking at that image.
So we are off to a fast start this season, it will be interesting to see what happens as the year progresses. For more interesting information and more data click on the link (http://www.cdc.gov/flu/weekly/#S2)
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