What does this weekly CDC data mean?

[Romana]

Here is the link:

http://www.cdc.gov/flu/weekly/

I had the flu during this week. The days with fever and aches were the 26th and 27th. I've done a couple online assessments and there's no doubt it was some strain of flu, rather than a cold, based on the symptoms.

So I went looking for the CDC data, to try to understand what I might have been exposed to. The entire family got sick, although I was the sickest and it was still pretty darn mild.

Looking at the CDC data, I'm having trouble understanding the import of the first chart. Why does is say "Data Cumulative for the Season" exactly where it seems to me it should be telling me what was circulating during this reporting week?

If you go down a little and look under "U.S. Virologic Surveillance," as far as I can tell it indicates that of the cases of flu monitored and reported during this reporting week, 99.7% of the "positive for flu" specimens were Type A, and it also says that more than 99% of those that they subtyped were H1N1. My understanding is that most doctors aren't bothering to subtype if it's Type A because all Type A circulating right now is H1N1. Am I correctly understanding that that's what this is saying?

Over 99% of all subtyped influenza A viruses reported to CDC this week were 2009 influenza A (H1N1) viruses.

That's found just underneath the second chart.

Does this mean that of cases tested and reported in the week in question, 99.7% were Type A and 99% of those were H1N1, with only 0.3% being Type B? In other words, if you got the flu during that week, you have more than 99% likelihood of having gotten H1N1? And only 0.3% likelihood of Type B?

Is this in any way influenced by virulence? That is, are the statistics skewed by H1N1 resulting in more hospitalizations or severe cases and thus being tested and reported at a higher rate than Type B?

Thanks to anyone who can help me interpret this data. I'd really like to understand the reporting better. FWIW, data for the prior week is almost identical.

Also, does the CDC publish similar data for other infectious diseases, like measles?

[tanyalynn]

One of the reasons that testing for type of influenza is rare right now is that for weeks and weeks, H1N1 has dominated the flu scene. Given how consistent the data has been for so long, and given that H1N1 isn't causing massive death rates (it's not shockingly more severe than other seasonal influenzas, we'd be seeing that by now), I think their data is probably accurate and not too skewed. Most people getting the flu right now are getting H1N1.