It's misleading because there is no evidence either way. It's just not been studied yet (in humans, at least -- it's been studied in other animals). Pretty muc

It's misleading because there is no evidence either way. It's just not been studied yet (in humans, at least -- it's been studied in other animals). Pretty much everyone equates "there's no evidence for X" to "X is wrong" in their mind. Maybe they are committing a logical fallacy, but the point of WHO's tweets is to provide accurate information to people. They can't just say "well, what we said is technically correct, so it's people's fault for not understanding!" A responsible way of conveying the same information would be "Whether people who have recovered from the virus are protected from a second infection is currently unknown". This way it doesn't seem to take a stance either way.