In recent weeks there has been increased discussion around the potential use of face shields as a tool to help prevent further spikes in infections of Covid-19.
Face shields are plastic face visors that provide full face protection. This type of face covering can play an important role in tackling the virus, but there are a number of misconceptions about how they work.
Face shields provide a high level of protection for the wearer. Given they cover the whole face – the mouth, nose and eyes – a high percentage of viral particles are prevented from reaching the wearer. Face shields are arguably best at protecting from coughs and sneezes.
Shields can therefore be very useful tools for those facing very regular contact, at close proximity, with others – for instance in medical settings. They also have great value in professions where nonverbal communication through facial expressions is important, such as teaching. They could be valuable in giving protection and confidence to teachers, enabling them to return to a classroom environment.
For this reason we recommend that face shields are procured and supplied to key groups such as teachers, health-care workers, emergency services staff, transport workers and those working in education.
Their use should also be encouraged in private sector settings such as retail, leisure and hospitality.
Masks are not as effective for coughs and sneezes, or heavy breathing during exercise. Therefore, they should be combined with face shields, to achieve broader protection. Face shields on their own, however, are not effective at protecting the wearer from airborne small speech droplets.
Face shields are valuable in protecting the wearer from inward inhalation of aerosol droplets that may be carrying the virus. While they offer some level of source control, since particles emitted through coughing and sneezing would be somewhat contained, they are less effective than masks when it comes to preventing the wearer from transmitting viral droplets outwards.
With this mind, the main purpose of face shields is to protect the wearer. Their effectiveness in this regard is enhanced because they are more likely than masks to be worn properly, and to be kept on for long periods of time. They are particularly useful, therefore, for those who are likely to have a lot of contact with the public.