If you wore a face shield during the pandemic, it probably didn’t offer you a high level of protection against Covid, according to new research from the University of East Anglia.
A study published today compared 13 face shield styles in controlled laboratory settings.
While all face shields provided some protection, none offered high levels of protection against external drops.
In addition to studying face shields in the lab, the research team surveyed people, including healthcare workers in middle-income countries (Brazil and Nigeria) about their views on face shields as PPE.
Face shields have been popular because they do not impede breathing, allow for more natural communication than face masks, and provide splash protection. They were widely used during the Covid pandemic. But until now there hasn’t been a huge amount of evidence about how protective they really are, especially given how people use them in the real world, and especially in poorer parts of the world.”
Paul Hunter, Professor, Norwich Medical School, University of East Anglia
“We wanted to learn more about how protective different styles of face shields might be, both in the lab and in real-world settings.”
UEA researchers worked with staff from the Health and Safety Executive (HSE), the UK’s occupational health and safety regulator, who tested 13 face shield designs in a controlled laboratory environment, using a “cough machine” that ejected fluorescent droplets onto mannequin heads.
The amount of contamination of the manikin’s face by the simulated cough drops was ranked from more to less.
Dr Julii Brainard, from UEA’s Norwich Medical School, said: “Laboratory tests showed that all face shields provided some protection, but none offered high levels of protection against external droplet contamination. The level of protection provided was influenced by design features, as well as which way the dummy’s head was turned when it was “coughed”.
“We found that large spaces around the sides, and sometimes the bottom or top, allow other people’s respiratory droplets to reach the face and that means exposure to potential viruses.
“The shields that offered the most protection were closed across the forehead and extended well down the sides of the face and below the chin.
“It’s important to know that the lab experiments are in the scenario of someone actively coughing on the shield wearer from close proximity. But the chances of the droplets surrounding the shield on the face just by talking are much higher get off.”
To learn more about how face shields are used in a real-world setting, the team surveyed more than 600 people in Nigeria and Brazil, including healthcare workers.
Dr Brainard said: “We wanted to know how users cleaned them and the things that mattered most when choosing face PPE during the pandemic.
“Unsurprisingly, we’ve found that people want proven protective products that are comfortable, stable on the head, easy to clean and don’t look weird.
“This study is important because the acceptability of facial PPE during the pandemic has been studied mainly in wealthier countries such as the UK or the US. The participants in our study were in Nigeria and Brazil and we should not assume that people in all countries see facial PPE the same way.
“It is also important to understand which design features of face shields might be more or less protective, so that people can choose the most effective designs.
“Finally, we wanted to know how people cleaned reusable face shields – methylated spirits or rubbing alcohol were popular, for example, but so was soap and water. Some cleaning chemicals might be incompatible with the face shield coatings. shield intended to prevent fogging or facilitate rapid drying. for example. Dust on the outside and fog inside the shields were also occasional problems,” he added.
“A Mixed Methods Study of the Effectiveness and Appropriateness of Face Shield Use as COVID-19 PPE in Middle-Income Countries” is published in the American Journal of Infection Control on July 28 2022.
In a related project, the HSE team tested face shields available for use in the UK. The results of this work, along with more details of the cough simulator, are published in the journal Annals of Work Exposures and Health.
Dr Brian Crook, HSE team microbiologist, said: “It is important that people using any type of PPE to protect themselves from infection know how effective it is, but also its limitations. We are working with an international standards committee to write guidance on a better means of providing this information.”
Source:
University of East Anglia