What's the control group?

Here's what the paper says about the evidence:

> Further high-quality research, including randomised trials of the optimum physical distance and the effectiveness of different types of masks in the general population and for health-care workers' protection, is urgently needed.

People who don't wear masks?

"We need more studies" is not the same as "our own study is bullshit". It's a simple statement of "there's something here that needs further confirmation".

In the meantime, I'm wearing a mask based on preliminary results, and the abject lack of "masks are actively dangerous" studies of any quality the anti-mask folks can refer to as a counterpoint.