Re "there is no evidence": this is due to a mismatch between the medical profession's use of the words "no evidence" and everyone else's.
To a standard human, "no evidence" means "there is no evidence".
To a medical professional, "no evidence" means "there is insufficient evidence for us to be certain".
The clash of terminology is very unfortunate, and it prevents one from discussing probabilities at all. A statement from the WHO is either that something is "certain" or that there is "insufficient evidence at this time", even if there is sufficient evidence for one to conclude something with 80% probability.
To a standard human, "no evidence" means "there is no evidence".
To a medical professional, "no evidence" means "there is insufficient evidence for us to be certain".
The clash of terminology is very unfortunate, and it prevents one from discussing probabilities at all. A statement from the WHO is either that something is "certain" or that there is "insufficient evidence at this time", even if there is sufficient evidence for one to conclude something with 80% probability.