Universal COVID-19 testing and a three-space triage protocol is associated with a nine-fold decrease in possible nosocomial infections in an inpatient psychiatric facility

•In May of 2020, the Substance Abuse and Mental Health Service Administration (SAMSA) issued guidelines for state psychiatric hospitals, recommending that these facilities adopt universal testing for COVID-19 and “three-space” triage protocols for dedicated COVID-19 positive, negative, and quarantine spaces to mitigate the risk of nosocomial infection.•Establishing and implementing such protocols can be costly and burdensome, raising questions about whether doing so is worth the associated institutional resources.•We reviewed the records of 1,139 patients treated on the inpatient service at the Westchester Behavioral Health Center of New York Presbyterian Hospital between March 14th and June 10th 2020, dates corresponding to the first COVID-19 surge in the New York City metropolitan region during and after the implementation of such a protocol. The completion of the protocol was associated with a 9-fold decrease in possible nosocomial infections.•Similar procedures can be applied to residential settings, including nursing homes or correctional facilities and can be scaled up or down over the course of pandemic, endemic or sporadic COVID-19 or of other infectious disease outbreaks. In May of 2020, the Substance Abuse and Mental Health Service Administration (SAMSA) issued guidelines for state psychiatric hospitals, recommending that these facilities adopt universal testing for COVID-19 and “three-space” triage protocols for dedicated COVID-19 positive, negative, and quarantine spaces to mitigate the risk of nosocomial infection. The Westchester Behavioral Health Center of New York Presbyterian Hospital (WBHC-NYP) adopted a comprehensive infection control protocol consistent with these recommendations in April, 2020. We reviewed the records of 1,139 patients treated on the inpatient service at WBHC-NYP between March 14th and June 10th, 2020, dates corresponding to the first COVID-19 surge in the New York City metropolitan region. The incidence of detected nosocomial or possible nosocomial infections before and during the implementation of the protocol was 0.096 (16/167), or 0.96 infections per 10 at-risk patients. The incidence of nosocomial or possible nosocomial infections after complete implementation was 0.0110 (2/182), or 1.1 infections per 100 at-risk patients. The difference in incidence between the two time points was statistically significant (p