Do face masks work? Earlier this year, the UK government decided that masks could play a significant role in stopping Covid-19 and made masks mandatory in a number of public places. But are these policies backed by the scientific evidence?
Yesterday marked the publication of a long-delayed trial in Denmark which hopes to answer that very question. The ‘Danmask-19 trial’ was conducted in the spring with over 3,000 participants, when the public were not being told to wear masks but other public health measures were in place. Unlike other studies looking at masks, the Danmask study was a randomised controlled trial – making it the highest quality scientific evidence.
Around half of those in the trial received 50 disposable surgical face masks, which they were told to change after eight hours of use. After one month, the trial participants were tested using both PCR, antibody and lateral flow tests and compared with the trial participants who did not wear a mask.
In the end, there was no statistically significant difference between those who wore masks and those who did not when it came to being infected by Covid-19. 1.8 per cent of those wearing masks caught Covid, compared to 2.1 per cent of the control group. As a result, it seems that any effect masks have on preventing the spread of the disease in the community is small.
Some people, of course, did not wear their masks properly. Only 46 per cent of those wearing masks in the trial said they had completely adhered to the rules. But even if you only look at people who wore masks ‘exactly as instructed’, this did not make any difference to the results: 2 per cent of this group were also infected.
When it comes to masks, it appears there is still little good evidence they prevent the spread of airborne diseases. The results of the Danmask-19 trial mirror other reviews into influenza-like illnesses. Nine other trials looking at the efficacy of masks (two looking at healthcare workers and seven at community transmission) have found that masks make little or no difference to whether you get influenza or not.
Last edited by KFWA; 11/19/20.
