Asymptomatic and Presymptomatic SARS-CoV-2 Infections in Residents of a Long-Term Care Skilled Nursing Facility — King County, Washington, March 2020 - MMWR Morb Mortal Wkly Rep 2020

27 March 2020:  https://www.cdc.gov/mmwr/volumes/69/wr/pdfs/mm6913e1-H.pdf

Key:

• Symptom-based screening could fail to identify approximately half of residents with COVID-19.
• Unrecognized asymptomatic and presymptomatic infections might contribute to transmission in these settings.
• Testing could guide cohorting strategies, or use transmission-based precautions for all residents of a facility after introduction of COVID-19.

Summary

• Setting: COVID-19 symptom assessments and COVID-19 testing in a long-term care skilled nursing facility in King County, Washington.
  • Symptom assessment (at day of testing or during preceding 14 days):
    Typical symptoms = fever, cough, and shortness of breath
    Atypical symptoms = sore throat, chills, increased confusion, rhinorrhea or nasal congestion, myalgia, dizziness, malaise, headache, nausea, and diarrhea. Symptomatic = at least one new or worsened typical or atypical symptom
    Asymptomatic = no symptoms or only stable chronic symptoms
    Presymptomatic = symptomatic within 7 days after testing
  • COVID-19 testing: nasopharyngeal swabs + RT-PCR.
• 76/82 (93%) of the residents were tested.
• 23/76 (30%) were COVID-19 positive, of which:
  • 10/23 (43%) were symptomatic
  • 13/23 (57%) were asymptomatic, of which 10/13 were presymptomatic.

Demographic characteristics were similar among the residents with negative and positive test results.