Summary: Background: The circulation of respiratory viruses poses a significant health risk among those residing in congregate settings. Data are limited on seasonal human coronavirus (HCoV) infections in homeless shelter settings. Methods: We analysed data from a clinical trial and SARS-CoV-2 surveillance study at 23 homeless shelter sites in King County, Washington between October 2019-May 2021. Eligible participants were shelter residents aged ≥3 months with acute respiratory illness. We collected enrolment data and nasal samples for respiratory virus testing using multiplex RT-PCR platform including HCoV. Beginning April 1, 2020, eligibility expanded to shelter residents and staff regardless of symptoms. HCoV species was determined by RT-PCR with species-specific primers, OpenArray assay or genomic sequencing for samples with an OpenArray relative cycle threshold