Will resolve to YES if the Global Polio Eradication Initiative (GPEI), WHO, or another qualified organization certifies the world as being free from polio before 2027.
From https://polioeradication.org/news-post/the-endgame-what-will-it-take-to-eradicate-polio/:
In 2020, GPEI launched a new roadmap to polio eradication, which set out two ambitious targets: firstly to permanently interrupt all poliovirus transmission in Pakistan and Afghanistan, stop transmission of cVDPV and prevent outbreaks in non-endemic countries by 2023. The second target is to certify the world free from polio – meaning no cases have been detected for three years – by 2026.
it really doesn't seem like 'have a few dozen people spend half an hour guessing at something' (forecasting) is a great technique for actually understanding something complex. it's better than 'have a bunch of people with bad local incentives tell you when it'll happen', but that's a low bar!