"From what I read, these are only useful if you're sick and trying to reduce transmission"

What government has said -- in a convoluted, almost misinformation manner -- is that from a probability perspective a mask is unlikely to be useful for an average person. They were saying this when the number of cases in the respective countries were single or double digit. But for front-line workers who by definition deal with a concentration of cases, it's much more effective and likely to be consequential.

But of course it's effective. It is a marvel that anyone seriously bought arguments to the contrary, and it is foolish misinformation that is going to plague us for years now.