Comments on: How many people die from influenza?

By: chauna sims

chauna sims — Fri, 12 Feb 2010 21:01:48 +0000

This is good information

By: chauna sims

chauna sims — Fri, 12 Feb 2010 13:01:48 +0000

This is good information

By: This Week In Virology – Esta Semana en Virología « Gripe por A (H1N1) Blog

Mon, 05 Oct 2009 17:07:38 +0000

[...] How many people die from influenza? [...]

By: profvrr

profvrr — Tue, 14 Jul 2009 20:24:21 +0000

Yes, the deaths reported as flu are variable, as discussed in the
post. That's why they are calculated statistically as a multiple of
P&I related deaths.

By: profvrr

profvrr — Tue, 14 Jul 2009 20:23:22 +0000

CFR for seasonal flu is calculated by determining excess P&I mortality
as described in the post. The number of infections is modeled based on
lab confirmed cases. I don't know why Argentina is concerned; they
should not be.

By: Some clarity on case fatality ratios | Swine Flu Daily Update

Some clarity on case fatality ratios | Swine Flu Daily Update — Mon, 13 Jul 2009 09:33:56 +0000

[...] Racaniello for his comment and the link to this excellent June 16 post on his virology blog: How many people die from influenza? Excerpt: …except in well-contained outbreaks in which the number of infected individuals can [...]

By: HansBonaire

HansBonaire — Sun, 12 Jul 2009 03:46:07 +0000

That sounds very plausible, but according to that same reasoning, isn't it possible that the same thing goes for the number of deaths? I mean that there are/could be 10 times more deaths because a lot of people don't even get tested or are being recognized as flu patients?

By: gonzo's wife

gonzo's wife — Thu, 02 Jul 2009 16:41:21 +0000

The question is… how do they determine the case fatality rate for typical seasons? Do they use mathematical modeling based on confirmed cases in surveillance? Do they use confirmed cases only? If there are truly over a million cases of H1N1 in the US, the CFR for the disease is .0001 or less. Way less than “seasonal influenza”. The hospitalization rate at near 15 % would be less than .3%, again, way less than seasonal flu. Without the ability to compare how the CFR is being determined between the H1N1 or the seasonal flu, how will we know whether next season will be concerning or not? and if Argentina usually has 2000 or more deaths a year from influenza, why are they concerned over 50 during their typical flu season?

By: profvrr

profvrr — Wed, 17 Jun 2009 16:47:21 +0000

I would say that any CFR based on laboratory confirmed cases is about
a ten-fold overestimate. There are probably at least ten times more
cases of influenza infection than those confirmed by laboratory tests.
See Chris Upton's comments here as well.

By: Chris Upton

Chris Upton — Wed, 17 Jun 2009 14:27:26 +0000

Tricky.
If it was really 1 in 200 dying, it would be total disaster.
One way to look at CFR might be to count deaths per hospitalization; not perfect either.
But it focuses on serious cases and outcome, rather than just whether we're testing for infection.
Numbers of hospitalizations is probably a better number than “confirmed cases”, as well.
At least it means a bit more to me.

By: Rob

Rob — Wed, 17 Jun 2009 14:09:13 +0000

Thank you for the post. I had one question:

CFR ratio =0.45% significant/insignificant?

In other words, how do I interpret CFR ratio? Is there any baseline below which its normal else significant?

By: gsgs

gsgs — Wed, 17 Jun 2009 04:18:09 +0000

published each week in MMWR (last page)
http://www.cdc.gov/mmwr/PDF/wk/mm5822.pdf
old weeks available

weekly deaths from pneumonia and influenza in New York City
weeks 17,2008 - 22,2009:

55,57,43,46,52,39,48,31,41,32,26,46,41,41,32,43,44,31,45,32,36,33,27,31,30,31,32,40,43,39,37,38,52,
42,25,??,51,63,52,60,52,54,53,47,55,43,46,49,45,61,45,33,34,32,44,23,51,30,42

average:42.5 per week

weeks 17-22,2009: 222 (37 per week)
weeks 17-22,2008: 292 (48.7 per week)

70 fewer deaths this year than in the same period last year.

~250 excess deaths from seasonality in NYC in 2008/9

15 weeks with most deaths : 53/2008-14/2009 = 776 (51.7 per week)
15 weeks with fewest deaths: 29/2008-43/2008 = 529 (35.3 per week)

no effect from Mexflu visible

By: Christian Sinclair

Christian Sinclair — Wed, 17 Jun 2009 02:48:04 +0000

Thanks for the great post. As a hospice physician who signs many death certificates, I had never once written influenza, so I always wondered how they got these numbers. Nor had I noticed it on discharge summaries or hospital progress notes. The true mortality rate is really unknown in this case.

Here is a post about the 1918 Influenza epidemic from a 3rd year medical student that was published a few years ago in Annals of Internal Medicine. http://arts.pallimed.org/2009/02/influenza-in-1...

(PS Found you via Research Blogging. Glad to see you using it, I do too at Pallimed)

By: Chris Upton

Chris Upton — Tue, 16 Jun 2009 20:27:13 +0000

Excellent info!
I think there's a lot of different types of good data collected on disease/death incidence but often it get reused in inappropriate ways.
The one that bugs me the most is calculating a case fatality rate on simple numbers of confirmed cases, when these are reported to be much lower than actual case number.
Thanks for the blog.