Face shields are protective but should be paired with other PPE
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Key takeaways:
- Wearing a face shield provided added protection from respiratory particles simulated by a cough machine.
- Particle concentration was generally much lower on the inside of the face shield compared to the outside.
When worn by health care personnel, a face shield was effective at reducing exposure to aerosol particles containing virus from a simulated coughing machine, researchers reported.
“This study started from our past research on virus bioaerosols,” Alessandra A. Pratt, PhD, MS, postdoctoral research fellow at the University of Iowa’s department of occupational and environmental health, told Healio. “With the start of the pandemic we transitioned to study the effectiveness of person protective equipment (PPE) in hospitals.”
To do so, Pratt and colleagues used an MS2 bacteriophage as a surrogate for SARS-CoV-2 which they aerosolized using a coughing machine to test on a simulated health care personnel (HCP) wearing a disposable plastic face shield placed 16 inches away.
According to the study, the aerosolized virus was sampled using SKC biosamplers inside the shield near the mouth of the simulated HCP, as well as on the outside of the face shield.
Overall, the study showed that there was a statistically significant reduction (P < .0006) in viable virus concentration on the inside of the face shield compared with that of the outside of the face shield. Specifically, they found that particle concentration was significantly lower on the inside of the face shield compared with that on the outside of the face shield for 12 of the 16 particle sizes measured (P < .05), with an RR reduction of 69%.
Based on these results, Pratt concluded that a face shield worn on an HCP was effective at reducing a clinician’s exposure to coughing bioaerosol. She explained that although it did not eliminate the risk of transmission entirely, it could reduce the severity of infection if there is a dose-response relationship.
“A face shield could still be protective if worn by [a] clinician when treating potentially infectious patients but may need to be paired with other respiratory protection to completely eliminate risk,” Pratt said.
“Face shields worn as a barrier protection device will prevent clinicians from having direct contact with splashes and sprays of potentially infectious materials and also prevents the clinician from touching their eyes, nose, and mouth, which can lead to indirect transmission and infection,” she said.
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