Case Investigations and Contact Tracing


Protecting communities, preventing the spread of disease

Public health professionals perform case investigations and contact tracing to help slow and prevent the spread of infectious diseases like COVID-19. Local health departments lead this work and the Washington State Department of Health and its partners support this work.

What does the interview process look like?

When public health learns that someone has tested positive for COVID-19, an interviewer may reach out to talk to that person, usually by phone – this is known as a case investigation.

When talking to the person who tested positive for COVID-19, interviewers work to determine their close contacts – anyone who has been within six feet of them for 15 minutes or more while they were infectious. Interviewers then reach out to inform close contacts of possible exposure. This is the next step to prevent the spread of disease, known as contact tracing. Interviewers do not reveal the name of the person who tested positive for COVID-19 when speaking with close contacts.

What will interviewers ask?

Interviewers use pre-approved questions for case investigations and contact tracing. They ask every person for their date of birth, address, race, and ethnicity, and other questions, along with questions related to your positive COVID-19 test or exposure. Interviewers will never ask for or write down immigration status, Social Security number, financial information, or marital status.

Information collected during interviews is used only by public health agencies. The information is protected in secure systems and individual information is not shared with anyone else. Interviewers operate under strict confidentiality rules.

Interviews are available in languages other than English. Outreach materials are available in more than 20 languages.

Every person interviewed receives guidance about how to keep themselves and others safe. Interviewers can also help connect people with resources they may need while they stay home for 5-10 days to ensure they are not sick (quarantine) or stay home to recover from being sick (isolation).

Why are these interviews important?

It's important to answer calls you receive from public health. When you do, it helps us:

  • Understand communities affected by COVID-19.
  • Inform public health actions.
  • Understand who is at risk.
  • Follow up with high risk groups.
  • Track the progress of the outbreak in our state.
  • Determine when it is safe to return to public life.