If H5N1 achieves global human-to-human spread, will it be a dud?

Question

Resolution criteria:

sustained human-to-human transmission is found on multiple continents

AND

< 400,000 estimated global deaths within first 12 months after sustained human-to-human transmission is found on multiple continents [date of official publication]

AND

Infection Fatality Rate* < 0.5%

AND

< 400,000 serious disabilities**

AND

serious disability rate per infection < 0.5%

*IFR = true mortality rate

**Serious disability: people losing 50% of their health, on scales such as WHODAS 2.0 or SF-36.

I will try to select credible sources for each claim. Unfortunately, neither meta-analysis nor CDC use good epidemiology for estimating long covid cases (they're overestimates - I say this as a long covid patient), although UK's Office of National Statistics had pretty decent methodology.

Reference points:

400k deaths is the estimated global amount for seasonal influenza,

https://academic.oup.com/aje/article/190/5/718/5903739?login=false

Swine flu was estimated as 284,400 (range, 151,700 to 575,400) but a cursory look seems like that's a high estimate based on CFR rather than IFR. 10-25% of world population got infected during the pandemic phase

https://www.cidrap.umn.edu/h1n1-2009-pandemic-influenza/cdc-estimate-global-h1n1-pandemic-deaths-284000

According to UK's [ONS](https://www.ons.gov.uk/peoplepopulationandcommunity/healthandsocialcare/conditionsanddiseases/bulletins/prevalenceofongoingsymptomsfollowingcoronaviruscovid19infectionintheuk/30march2023) about 0.4% of the UK population have long covid with a severity that limits their daily activity a lot

I no longer bet on any of my own questions

Update 2025-02-01 (PST) (AI summary of creator comment): Additional Resolution Criterion:

Market will resolve as N/A if H5N1 does not achieve sustained human-to-human transmission on multiple continents by the closing date.

Manifold Markets · Answer

Roughly even odds — Manifold Markets prediction market estimates a 42% chance (9 traders, as of Mar 8, 2025).