There is huge difference between "no evidence of human to human transmission" and "evidence of no human to human transmission". The former means, we don't know

There is huge difference between "no evidence of human to human transmission" and "evidence of no human to human transmission". The former means, we don't know yet. You can blame them for not knowing. But admitting that was right. And when they knew, they told everyone. At least in this instance, they haven't lost any credibility. On the contrary, it shows integrity to admit your limits of knowledge.