Face coverings to reduce transmission of SARS-CoV-2
Face masks to reduce transmission of COVID-19: A rapid review
OVID-19 can be transmitted by droplets breathed out by an infected person. Face masks may have a role in reducing transmission of the disease by containing droplets and preventing them reaching other people and/or by preventing the person wearing a face mask from breathing in droplets present in the air.
This review looks at the evidence as to whether face masks reduce transmission of COVID in the community and whether some masks are better than others.
The evidence at this point remains limited. Studies are of low quality. The results of studies may be skewed by other factors. People wearing masks may be changing their behaviour in other ways that affect the likelihood of them catching COVID. There is no specific evidence available about face masks to prevent transmission of COVID in particular settings such as schools and public transport or at different times of year. Neither is there any evidence on the effect of wearing masks by children and young people. The evidence does not show if any reduction in transmission is as a result of the wearer being protected from breathing in droplets in the air or by protecting everyone else from droplets breathed out by the person wearing the mask.
Do face masks make a difference?
- Face masks may provide benefits in preventing transmission of COVID-19 but higher quality studies suggest these benefits may be modest.
- Commonly used face masks do filter droplets to some extent. Medical masks appear to do this better than fabric masks although some studies suggest they are the same.
Are there any negative effects of wearing masks?
- There was no indication of serious harm from wearing face masks.
- Some people report discomfort or the feeling of it being difficult to breathe.
- There are concerns about the effect on the environment of so many non-biodegradable products.
Policy and practice implications
- Face masks may play a role in preventing transmission of COVID-19 over the next phases of the pandemic.
- Face masks are usually part of a bundle of measures (hand washing, social distancing, ventilation etc) and most evidence is in this context. Mask-wearing alone, in the absence of other preventive measures, may not be effective.
- Higher quality studies suggest face masks may have a modest effect
- There may be benefits from providing public health messages on characteristics of face masks that appear to be more effective (medical rather than fabric masks) and how to use them effectively by mask both nose and mouth.
- There is no clear evidence to indicate that specific patient populations, including people with medical conditions and children, should be routinely exempted from wearing face masks.
RR00007