Effectiveness and adherence to closed face shields in the prevention of COVID-19 transmission: a non-inferiority randomized controlled trial in a middle-income setting (COVPROSHIELD)

Abstract

Background The use of respiratory devices can mitigate the spread of diseases such as COVID-19 in community settings. We aimed to determine the effectiveness of closed face shields with surgical face masks to prevent SARS-CoV-2 transmission in working adults during the COVID-19 pandemic in Bogotá, Colombia. Methods An open-label non-inferiority randomized controlled trial that randomly assigned participants to one of two groups: the intervention group was instructed to wear closed face shields with surgical face masks, and the active control group was instructed to wear only surgical face masks. The primary outcome was a positive reverse transcription polymerase chain reaction test, IgG/IgM antibody test for SARS-CoV-2 detection, or both during and at the end of the follow-up period of 21 days. The non-inferiority limit was established at − 5%. Results A total of 316 participants were randomized, 160 participants were assigned to the intervention group and 156 to the active control group. In total, 141 (88.1%) participants in the intervention group and 142 (91.0%) in the active control group completed the follow-up. Primary outcome: a positive SARS-CoV-2 test result was identified in one (0.71%) participant in the intervention group and three (2.1%) in the active control group. In the intention-to-treat analysis, the absolute risk difference was − 1.40% (95% CI [− 4.14%, 1.33%]), and in the per-protocol analysis, the risk difference was − 1.40% (95% CI [− 4.20, 1.40]), indicating non-inferiority of the closed face shield plus face mask (did not cross the non-inferiority limit). Conclusions The use of closed face shields and surgical face masks was non-inferior to the surgical face mask alone in the prevention of SARS-CoV-2 infection in highly exposed groups. Settings with highly active viral transmission and conditions such as poor ventilation, crowding, and high mobility due to occupation may benefit from the combined use of masks and closed face shields to mitigate SARS-CoV-2 transmission. Trial registration ClinicalTrials.gov NCT04647305. Registered on November 30, 2020

Effectiveness of face masks for reducing transmission of SARS-CoV-2: a rapid systematic review

“…[46]observationalUSAmasks for reducing transmissionPCRquestionnaireVarela et al . [47]RCTColombiatypes of masksRT-PCR or serology (rapid antibody test)photograph confirmation of mask use; questionnaire; interviewWang et al . [48]observationalChinamasks for reducing transmissionRT-PCR or serology (non-specific)questionnairehealthcare settingsAdawee et al .…”

“…In the implementation cluster RCT cited above [14], surgical masks were associated with an 11.1% reduction in symptomatic seroprevalence (aPR 0.89 [95% CI: 0.78, 1.00]) compared with no statistically significant effect of cloth masks (aPR 0.94 [95% CI: 0.78, 1.10]). The other RCT [47] compared use of a closed face shield with surgical face mask to using a surgical mask alone to prevent SARS-CoV-2 infection. Only one participant tested positive for SARS-CoV-2 in the mask-only group versus three participants in the mask plus shield group.…”

“…Nineteen studies compared the effectiveness of different types of masks for reducing transmission of SARS-CoV-2: four studies (two RCTs, two observational) in community settings [14,16,23,47] and 15 studies (one RCT, 14 observational) in healthcare settings [50,52,57,68,[70][71][72][73][74]78,80,[82][83][84]88].…”