The experts warn that plastic face shields being used in many hair salons are unlikely to be an effective control for aerosol transmission of Covid-19.
In documents released by the UK's Scientific Advisory Group for Emergencies (Sage) on Friday , the New and Emerging Respiratory Virus Threats Advisory Group (Nervtag) says the guidance needs to change.
The group says face shields provide protection for the wearer against large droplet exposure, including by inoculation through the eyes.
However, they are unlikely to provide any protection for the wearer against small aerosols.
There is no evidence that face shields/visors are an effective source control for either larger droplets or small aerosols, the document published on Friday sets out.
In the paper from July 22nd, the scientists advise: “It is recommended that guidance for settings where people are in close proximity for a long duration (eg hairdressing), and that currently only require face shields to be worn, should be changed to include the wearing of face coverings.”
In the document released by Sage, the scientists note that an anecdotal report from an outbreak in Switzerland has suggested those wearing face shields were more likely to be infected than those wearing masks.
However they warn this should be treated with caution as the outbreak investigation has not yet formally reported.
