No evidence of something is not the same as evidence of (not something). No evidence that Person A is the murderer does not mean there is evidence that he is n

No evidence of something is not the same as evidence of (not something). No evidence that Person A is the murderer does not mean there is evidence that he is not the murderer(e.g. alibi). Evidence may turn up later on that he was indeed the murderer. WHO said that there was no evidence of human to human transmission. They did not say they found evidence that it is not transmissible from human to human. That's a world of difference.