C Raina MacIntyre1, Holly Seale1, Tham Chi Dung2, Nguyen Tran Hien2, Phan Thi Nga2, Abrar Ahmad Chughtai1, Bayzidur Rahman1, Dominic E Dwyer3, Quanyi Wang4
Objective The aim of this study was to compare the efficacy of cloth masks to medical masks in hospital healthcare workers (HCWs). The null hypothesis is that there is no difference between medical masks and cloth masks.
Setting 14 secondary-level/tertiary-level hospitals in Hanoi, Vietnam.
Participants 1607 hospital HCWs aged ≥18 years working full-time in selected high-risk wards.
Intervention Hospital wards were randomised to: medical masks, cloth masks or a control group (usual practice, which included mask wearing). Participants used the mask on every shift for 4 consecutive weeks.