A mixed methods study on effectiveness and appropriateness of face shield use as COVID-19 PPE in middle income countries

Background: Face shields were widely used in 2020-2021 as facial personal protective equipment (PPE). Laboratory evidence about how protective face shields might be and whether real world user priorities and usage habits conflicted with best practice for maximum possible protection was lacking – especially in limited resource settings. Methods: Relative protective potential of 13 face shield designs were tested in a controlled laboratory setting. Community and health care workers were surveyed in middle income country cities (Brazil and Nigeria) about their preferences and perspectives on face shields as facial PPE. Priorities about facial PPE held by survey participants were compared with the implications of the laboratory-generated test results. Results: No face shield tested totally eliminated exposure. Head orientation and design features influenced the level of protection. Over 600 individuals were interviewed in Brazil and Nigeria (including 240 health care workers) in March-April 2021. Respondents commented on what influenced their preferred forms of facial PPE, how they tended to clean face shields, and their priorities in choosing a face cover product. Surveyed health care workers commonly bought personal protection equipment for use at work. Conclusions: All face shields provided some protection but none gave high levels of protection against external droplet contamination. Respondents wanted facial PPE that considered good communication, secure fixture, good visibility, comfort, fashion, and has validated protectiveness.