Is face mask with face shield more effective than face mask alone in reducing SARS-CoV-2 transmission? A systematic review

ABSTRACT

@#<p style="text-align justify;"><strong>Background.</strong> The use of face shield in addition to face mask is thought to reduce the transmission of SARS-CoV-2 by blocking respiratory droplets and by preventing one from touching facial orifices.</p><p style="text-align justify;"><strong>Objective.</strong> To determine the effectiveness of face mask with face shield, compared to face mask alone, in reducing transmission of SARS-CoV-2.</p><p style="text-align justify;"><strong>Methods.</strong> We searched MEDLINE, Cochrane Library, as well as trial registers, preprint sites and COVID-19 living evidence sites as of 30 September 2021. We included studies that used face shield with face mask versus face mask alone to prevent COVID-19. We screened studies, extracted data, assessed the risk of bias and certainty of evidence using the GRADE approach. Review Manager 5.4 was used to estimate pooled effects.</p><p style="text-align justify;"><strong>Results.</strong> There is no available direct evidence for face shield plus face mask versus face mask alone in the general public. Five (5) observational studies with very low certainty of evidence due to serious risk of bias and indirectness were included. Participants in all the studies were health care workers (HCWs) who used the face shield with their standard personal protective equipment (PPE). Four (4) of the studies were in the hospital setting (three case control studies, one pre- and post-surveillance study); one was done in the community (one pre- and post-surveillance study) in which HCWs visited the residence of the contacts of SARS-CoV-2 positive patients. The case control studies done in the hospital setting showed a trend toward benefit with the use of face shield or goggle but this was inconclusive (OR 0.85, 95% CI 0.68-1.08) while the pre- and post-surveillance study showed significant benefit when face shield (OR 0.28, 95% CI 0.22-0.37) use became a requirement for HCWs upon hospital entry. In the study done in the community setting, significant protection for HCWs was noted with the use of face shield (OR 0.04, 95% CI 0.00-0.69) but the results were limited by serious risk of bias and imprecision.</p><p style="text-align justify;"><strong>Conclusion.</strong> In the hospital setting, there was a lower likelihood of COVID-19 infection in HCWs who used a face shield or goggles on top of their PPE. For the general public in the community, there is presently no study on the use of face shield in addition to the face mask to prevent COVID-19 infection.</p>