The impact of less restrictive quarantine for exposed COVID-19 patients in inpatient psychiatric settings: a cohort analysis.

Objective: To quantify the impact of a changing cohort strategy on COVID-19 transmission in an acute inpatient behavioral health facility.

Design: Cohort study.

Patients: Behavioral health inpatients exposed to COVID-19.

Interventions: This cohort project compared COVID-19 conversion rates during two periods. In the first period (July 2020-April 2022), exposed patients (regardless of vaccination status) were cohorted separately from unexposed individuals. In the second period (May 2022-September 2022), exposed vaccinated patients remained with unexposed patients. COVID-19 conversion was identified through post-exposure asymptomatic testing or test-confirmed symptom development, with rates quantified per all admissions, per 10,000 patient days at risk, and per patient-specific exposure.

Results: The 27-month project included 11,761 admissions and 164,762 patient days of care. The proportion of patients up-to-date on COVID-19 vaccination at admission and discharge ranged from 11%-19%. The second period showed an increased risk of SARS-CoV-2 conversion per admission (1.87% vs 0.36%, P < 0.001) and per 1,000 patient-days at risk (1.44 vs 0.27 conversions per 1,000 patient days, P < 0.001), but not per exposure (3.44% vs 3.13%, P = 0.68).

Conclusions: Reducing the population of patients cohorted after a SARS-COV-2 exposure is associated with increased risk of SARS-COV-2 transmission in inpatient psychiatric settings.