A review of the studies done so far has concluded that wearing masks really does help prevent the spread of covid-19. It is far from the first paper to come to this finding, so why does the issue remain so controversial? The problem is that it isn’t easy to carry out individual studies of the highest standard during a pandemic. That standard is a randomised controlled trial (RCT), in which people are randomly assigned to either get a treatment or intervention, in this case wearing a mask, or not. Because of the practical difficulties, only two RCTs have looked at...
