It's the difference between IFR and CFR. The IFR is the infection fatality rate meaning everyone in the population who has been infected. The CFR is the case fatality rate, those who are sick enough to show up at a hospital, or well, get tested and confirmed positive. Which nowadays is essentially the same and a small fraction of total cases.
We see here that flu seems to have an overall IFR rate of 0.002%. Many orders of magnitude smaller than COVID19.
According to the CDC, the seasonal flu kills 12,000-79,000 Americans a year by the same standard as used for COVID-19. Much closer to the widely cited 0.1% IFR.
CEBM concurs, the H1N1 CFR was between 0.1% and 5.1%, based on country and the fatality risk settled out at 0.02%. [1]
Some more napkin math, the CDC estimates between 12,000 and 61,000 flu fatalities per year out of approximately 9,300,000 to 45,000,000 infections so pretty consistently a 0.1-0.15% IFR. [2]
Not sure how to reconcile these. The worst year, 2017-2018, had 45M cases and 61K deaths. The dominant strain was H3N2 not H1N1. The vaccine wasn't particularly effective that year (38%). Not sure how else to account for the delta. [3, 4]
By doing serologic studies you can estimate the global number of contaminated people: looking at the number of viral mutations, as well as different strands of the virus that can be identified as being generated in a specific region.
It’s going to be very imprecise. For H1N1 the global infection rate could have varied from 11% to 21% of the global population, which is a +/- 350 million people estimation.
The IFR rate for covid-19 seems to be trending towards 0.1-0.5% based on the serological tests over entire population cohorts that are starting to be published.
The IFR rate for covid-19 seems to be trending towards 0.1-0.5% based on the serological tests over entire population cohorts that are starting to be published.
We see here that flu seems to have an overall IFR rate of 0.002%. Many orders of magnitude smaller than COVID19.
https://www.cdc.gov/nchs/fastats/flu.htm