Because while we do have clear data in the US and what the US variant can do, we do not have clear data on what is happening in China right now. That's the difference. Ana that's all WHO is asking right now, more data so that the rest of the world can know whether to take extra precautions or would that be unnecessary.

And until we have clear data it's reasonable for the rest of the world to assume the worse and try to protect itself. And maybe the collective action of the rest of the world in requiring travelers from China to have negative tests, can help in pressuring the Chinese government to make their data more transparent to avoid the international reactionary restrictions.

Wearing a mask is good practice but it's obviously not foolproof. We don't know whether the new vaccines will be helpful if we aren't even sure of what new variants there may be.