We included three trials, involving a total of 2106 participants. There was no statistically significant difference in infection rates between the masked and unmasked group in any of the trials. We identified no new trials for this latest update.
From the limited results it is unclear whether the wearing of surgical face masks by members of the surgical team has any impact on surgical wound infection rates for patients undergoing clean surgery.
- If you are healthy, you only need to wear a mask if you are taking care of a person with COVID-19.
- Wear a mask if you are coughing or sneezing.
- Masks are effective only when used in combination with frequent hand-cleaning with alcohol-based hand rub or soap and water.
- If you wear a mask, then you must know how to use it and dispose of it properly.
In conclusion, as opposed to Greenhalgh et al., we believe that the context of the current covid-19 pandemic is very different from that of the “parachutes for jumping out of aeroplanes”, in which the dynamics of harm and prevention are easy to define and even to quantify without the need of research studies. It is necessary to quantify the complex interactions that may well be operating between positive and negative effects of wearing surgical masks at population level. It is not time to act without evidence.
[D]oes any of what is out there add up to a watertight case for compelling people to wear masks in public or at work (outside a healthcare setting)? The threshold for compulsion must surely be higher than ‘maybe’ and ‘perhaps’. But if it really is the case that the threshold for regulatory compulsion is being approached, it should be a simple matter for our scientific advisors to present it to us and allow time for it to be critically discussed in relation to a real-world setting, before government imposes measures upon us all.
Speaking may be a primary mode of transmission of SARS-CoV-2. Considering that reports of asymptomatic transmission account for 50-80% of COVID-19 cases and that saliva has peak viral loads at time of patient presentation, droplet emission while speaking could be a significant factor driving transmission and warrants further study. We used a planar beam of laser light passing through a dust-free enclosure to detect saliva droplets emitted while speaking. We found that saying the words ‘Stay Healthy’ generates thousands of droplets that are otherwise invisible to the naked eye. A damp homemade cloth face mask dramatically reduced droplet excretion, with none of the spoken words causing a droplet rise above the background. Our preliminary findings have important implications for pandemic mitigation efforts.