Minimising the duration of N95 respirator use during hospital SARS-CoV-2 outbreaks: A mixed-effects analysis of post-screening infection reduction.

Hospital SARS-CoV-2 outbreaks require effective interventions. We evaluated targeted universal N95 respirator use among staff from outbreak identification until screening results. Analysing 18 cluster outbreaks using generalised linear mixed models, we found that N95 respirator use was associated with a 72% reduction in new infections (P<0.001) compared to surgical masks. The mean duration of N95 respirator use was 5.25 days. Policy effectiveness was independent of outbreak size. Bootstrap analysis confirmed significant reduction (mean difference -3.02 cases, 95% CI: -5.98 to -0.08). Infection source showed substantial variability while ward-level variation was minimal. Short-term targeted N95 respirator use effectively controls hospital outbreaks while optimising resources and staff comfort.