The problem with this, is that people want action items. No one wants to go to the WHO and find out nothing about the virus. If you wanted to do that, you could

The problem with this, is that people want action items. No one wants to go to the WHO and find out nothing about the virus. If you wanted to do that, you could go anywhere. So they're encouraged to put something down. That something was wrong. It happens, it's a group run by humans. It would be great if they got everything correct, but unfortunately they don't, and to make matters worse, it sounds like they're an organization driven by consensus so changing minds means changing a bunch of individual doctors minds. Take it from me that changing doctors' minds on things is a sisyphean task. We're lucky we got a correction in 2 years. Hopefully they learned something for any further pandemics. But the other factor of this is that communicating to people is difficult, and if you change your mind publicly and loudly too many times people lose faith in you. And unfortunately faith/belief is what people need to have in the WHO for it to be effective at giving advice.