SARS-CoV-2 Breakthrough Infections and Reinfections in Patients with Severe Mental Illness during Three Omicron Outbreaks.

Patients with severe mental illness (SMI) in psychiatric facilities face unique vulnerabilities to severe acute respiratory syndrome coronavirus-2 infection. We conducted an study in a female-only, closed psychiatric ward from February 2020 to December 2023, documenting three coronavirus disease 2019 outbreaks during BA.2, BA.5, and XBB-predominant periods. During the first outbreak, 98.0% of residents were infected, including 97.7% of vaccinated individuals. The second outbreak resulted in 28.6% infections, with 25.5% experiencing presumed reinfection. The third outbreak affected 78.0% of residents. All infections were mild with no hospitalizations or deaths. These findings highlight the vulnerability of institutionalized SMI populations.