I think communicating uncertainty has been a weakness of virtually all public health authorities in this response. It's a really core part of good public health communication. I think the WHO has not done well enough in proactively communicating uncertainty.
With a novel virus, we don't know everything. At the beginning, we're working from the closest parallels we see. What do we know about influenza? What do we know about SARS? What do we know about MERS? Those are the closest things to this virus, so we'll recommend what we know about those viruses, and then, as we learn more about this one, we can refine it.
I don't think that process was well explained or well communicated. It's really important—this is written into the CDC communications guidelines—to communicate up front the uncertainty, to say that the guidance will change, so bear with us. You will know what we know as we know it.