Do masks really halve the risk of Covid? A note on the evidence – The Spectator

The analysis identified 72 studies that might potentially have provided evidence on the effectiveness of masks, social distancing and hand washing. Of those, just six (not eight, 30 or 72) were sufficiently relevant — and of sufficient quality — that they could provide any useful information on mask efficacy. And how reliable were the six? Four were assessed to have a moderate risk of bias, and two to have a serious or critical risk.