Prolonged persistence of PCR-detectable virus during an outbreak of SARS-CoV-2 in an inpatient geriatric psychiatry unit in King County, Washington.

Background: We describe key characteristics, interventions, and outcomes of a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak within an inpatient geriatric psychiatry unit at the University of Washington Medical Center - Northwest.

Methods: After identifying 2 patients with SARS-CoV-2 infection on March 11, 2020, we conducted an outbreak investigation and employed targeted interventions including: screening of patients and staff; isolation and cohorting of confirmed cases; serial testing; and enhanced infection prevention measures.

Results: We identified 10 patients and 7 staff members with SARS-CoV-2 infection. Thirty percent of patients (n = 3) remained asymptomatic over the course of infection. Among SARS-CoV-2 positive patients, fever (n = 5, 50%) and cough (n = 4, 40%) were the most common symptoms. Median duration of reverse transcription polymerase chain reaction (RT-PCR) positivity was 25.5 days (interquartile range [IQR] 22.8-41.8) among symptomatic patients and 22.0 days (IQR 19.5-25.5) among asymptomatic patients. Median initial (19.0, IQR 18.7-25.7 vs 21.7, IQR 20.7-25.6) and nadir (18.9, IQR 18.2-20.3 vs 19.8, IQR 17.0-20.7) cycle threshold values were similar across symptomatic and asymptomatic patients, respectively.

Conclusions: Asymptomatic infection was common in this cohort of hospitalized, elderly individuals despite similar duration of SARS-CoV-2 RT-PCR positivity and cycle threshold values among symptomatic and asymptomatic patients.