Epidemiology of Covid-19 in a Long-Term Care Facility in King County, Washington

BACKGROUND Long-term care facilities are high-risk settings for severe outcomes from outbreaks of Covid-19, owing to both the advanced age and frequent chronic underlying health conditions of the residents and the movement of health care personnel among facilities in a region.

METHODS After identification on February 28, 2020, of a confirmed case of Covid-19 in a skilled nursing facility in King County, Washington, Public Health–Seattle and King County, aided by the Centers for Disease Control and Prevention, launched a case investigation, contact tracing, quarantine of exposed persons, isolation of confirmed and suspected cases, and on-site enhancement of infection prevention and control.

RESULTS As of March 18, a total of 167 confirmed cases of Covid-19 affecting 101 residents, 50 health care personnel, and 16 visitors were found to be epidemiologically linked to the facility. Most cases among residents included respiratory illness consistent with Covid-19; however, in 7 residents no symptoms were documented. Hospitalization rates for facility residents, visitors, and staff were 54.5%, 50.0%, and 6.0%, respectively. The case fatality rate for residents was 33.7% (34 of 101). As of March 18, a total of 30 long-term care facilities with at least one confirmed case of Covid-19 had been identified in King County.

CONCLUSIONS In the context of rapidly escalating Covid-19 outbreaks, proactive steps by long-term care facilities to identify and exclude potentially infected staff and visitors, actively monitor for potentially infected patients, and implement appropriate infection prevention and control measures are needed to prevent the introduction of Covid-19.


  • Temet M. McMichael, Ph.D.,
  • Dustin W. Currie, Ph.D.,
  • Shauna Clark, R.N.,
  • Sargis Pogosjans, M.P.H.,
  • Meagan Kay, D.V.M.,
  • Noah G. Schwartz, M.D.,
  • James Lewis, M.D.,
  • Atar Baer, Ph.D.,
  • Vance Kawakami, D.V.M.,
  • Margaret D. Lukoff, M.D.,
  • Jessica Ferro, M.P.H.,
  • Claire Brostrom-Smith, M.S.N.,
  • et al., for the Public Health–Seattle and King County, EvergreenHealth, and CDC COVID-19 Investigation Team*

27 March 2020