Seasonal Flu -- A Look Back -- Sunday, February 19, 2023

Other than starting one year earlier and ending one year earlier (the top graph), the two graphs below both have the same heading:

"Cumulative rate of laboratory-confirmed influenza hospitalizations among cases of all ages...." Only the ranges are different.

• The top graph: "2015-16 to 2021-22." 

• The bottom graph: "2014-15 to 2022-23."

Can you spot the differences?

Top graph:

Bottom graph:

What I observed:

The top graph, "2015-16 to 2021-22" should cover seven flu seasons (count them: 16, 17, 18, 19, 20, 21, 22).

The bottom graph, "2014-15 to 2022-23" should cover nine flu seasons (count them: 15, 16, 17, 18, 19, 20, 21, 23).

Now, count the number of lines in each graph:

The top graph should have seven lines; it has eight.

The bottom graph should have nine lines; it does; it has nine lines.

The top graph "heading" suggests only seven seasons, whereas the bottom graph "heading" now suggests nine seasons. Why the change? Macht nichts.

Both graphs stop at week 15 (top graph) or week 17 (bottom graph). Macht nichts.

There is one exception, in the bottom graph year 2021 - 2022 goes out to week 23. Why? Macht nichts. 

But this is what caught my eye. Let's go back to the number of lines in each graph vs the heading.

The lower/bottom graph is fine.

The heading in the top/upper graph covers seven "flu" seasons. And, yet there are eight lines -- representing eight flu seasons.

Remarkably (and/or fortuitously), that graph also included the cumulative rate for the 2011-12 flu season. 

Look at the top graph.

During the 2020-21 and 2021-22 Covid-19 pandemic, "seasonal flu" practically disappeared, practically off the scale (trending toward zero) compared to all the other seasons prior to the Covid-19 pandemic.

With one exception: the 2011-12 "flu season."

That "flu season," -- 2011-12 -- a decade before the Covid-19 pandemic, was also a year that had virtually no "seasonal flu."

So what happened?

The CDC did not address that at the time this graph was posted (unless I missed it).

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The 2011 - 2012 "Flu Season"

Googling.

The CDC actually addressed the question: the 2011 - 2012 flu season. Link here.  

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Others

A few other sites addressed the very, very unusual phenomenon observed in 2011 - 2012.

Waning effectiveness of the "flu" vaccine during the 2011 - 2012 "flu" season. Link here.  

Quiet season: where is the flu? Link here.

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The Swine Flu Epidemic

WHO:

• H1N1/swine flu/influenza virus
• June, 2009, to August, 2010

Is it just my imagination or do others recall this also:  in 2009, the GOP did not question the WHO with regard to swine flu, but one of the GOP's favorite targets with regard to Covid 19 was the WHO.