Could Covid-19 face shields be giving us a false sense of security?

Tests run using a Japanese supercomputer have found these bits of PPE to be less efficient than masks in protecting against the spread of the virus

07 October 2020 - 11:03 By Sanet Oberholzer
Dr Susan Louw previously told TimesLIVE that if you're only going to be wearing a face shield, it needs to come to below your chin and wrap around your face completely.
Dr Susan Louw previously told TimesLIVE that if you're only going to be wearing a face shield, it needs to come to below your chin and wrap around your face completely.
Image: Ethan Miller/Getty Images

Face shields may be providing us with a false sense of security when it comes to safeguarding against Covid-19.

According to a simulation that was done using Fugaku, the world’s fastest supercomputer housed at the RIKEN Center for Computational Science in Japan, plastic face shields are almost completely ineffective when it comes to trapping respiratory aerosols.

According to the research released by RIKEN, in a simulation that combined air flow with the reproduction of droplets of different sizes, close to 100% of droplets that were smaller than 5 micrometres (one millionth of a metre) escaped through the gap between a person’s face and a plastic face shield. When testing larger droplets of 50 micrometres, 50% of the droplets escaped.

Speaking to The Guardian, Makoto Tsubokura, team leader at the centre, said when compared to masks, face shields are less effective in preventing the spread of droplets from an infected person’s mouth.

In a previous interview with TimesLIVE, Dr Susan Louw, a haematopathologist at SA's National Health Laboratory Service, explained: “When you’re wearing a mask you’re also protecting your fellow human beings against you sneezing and coughing and transmitting the virus to them. A face shield might still allow virus to escape and infect the person that is standing next to you.”

Speaking on the same topic, Prof Wolfgang Preiser, head of medical virology at Stellenbosch University’s department of pathology, said face shields may offer an additional degree of protection against Covid-19 as long as you wear them in conjunction with a face mask and observe the correct social distancing protocols.

Tsubokura added that individuals who have been advised not to wear masks for reasons such as underlying respiratory problems could wear face shields, provided this is done outdoors or in well-ventilated indoor settings.