IFR for flu is less than 0.1% according to the CDC.

https://www.cdc.gov/flu/about/burden/index.html

That's not the IFR since they're not counting asymptomatic cases (based on a quick read)

They don't mention IFR anywhere as far as I can see

Thanks. I have seen serious estimates of 0.1% CFR for the 1957 and 1964 flu pandemics, but only notes saying that the seasonal flu CFR is <0.1%. Do you have a source for the 0.04% IFR?

No (hence the question mark), I'm seeing 0.04% pop up everywhere but I haven't found the source for the number.

But it seems plausible if the CFR is <0.1% as there are both asymptomatic cases of the flu and people don't always go to the doctor even if they have symptoms. It seems like caring about IFR was rare before this pandemic and the lockdown

Got it. Thanks. I think it may be because the IFR is less reliable, since for most diseases it requires a gross estimation the real number of infected persons. It is probably more popular these days because people are putting a lot of effort into the comparisons with the seasonal flu.