Important update: Healthcare facilities
CDC has updated select ways to operate healthcare systems effectively in response to COVID-19 vaccination. Learn more
Given new evidence on the B.1.617.2 (Delta) variant, CDC has updated the guidance for fully vaccinated people. CDC recommends universal indoor masking for all teachers, staff, students, and visitors to K-12 schools, regardless of vaccination status. Children should return to full-time in-person learning in the fall with layered prevention strategies in place.
The White House announced that vaccines will be required for international travelers coming into the United States, with an effective date of November 8, 2021. For purposes of entry into the United States, vaccines accepted will include FDA approved or authorized and WHO Emergency Use Listing vaccines. More information is available here.
Travel requirements to enter the United States are changing, starting November 8, 2021. More information is available here.

Interim Guidance on Developing a COVID-19 Case Investigation & Contact Tracing Plan: Overview

Interim Guidance on Developing a COVID-19 Case Investigation & Contact Tracing Plan: Overview
Updated Feb. 28, 2022

Universal case investigation and contact tracing are not recommended. This guidance can be used for investigation of priority cases and notification of priority close contacts outlined in the Prioritizing Case Investigation and Contact Tracing for COVID-19 guidance.

A checklist is available to assist health departments pdf icon[417 KB, 6 pages] in developing a comprehensive plan. This tool does not describe mandatory requirements or standards; rather, it highlights important areas for consideration.

Content will be updated as new information is available.


Case investigation* and contact tracing are fundamental activities that involve working with a patient (symptomatic and asymptomatic) who has been diagnosed with an infectious disease to identify and provide support to people (contacts) who may have been infected through exposure to the patient. This process prevents further transmission of disease by separating people who have (or may have) an infectious disease from people who do not. It is a core disease control measure that has been employed by public health agency personnel for decades. Case investigation and contact tracing are most effective when part of a multifaceted response to an outbreak.

Key Considerations for COVID-19

  • Since COVID-19 can be spread before symptoms occur or when no symptoms are present, case investigation and contact tracing activities must be swift and thorough.
  • The complete clinical picture of COVID-19 is not fully known. As scientists learn more, updates may be made to recommendations for testing priorities and the window period (when the patient was infectious and not under isolation) in which contacts should be elicited.
  • Remote communications for the purposes of case investigation and contact tracing should be prioritized; in-person communication may be considered only after remote options have been exhausted.
  • Given the potentially large number of cases and contacts, jurisdictions may need to prioritize case investigation and contact tracing activities. Prioritization should be based on vulnerability, congregate settings/workplaces and healthcare facilities, including long-term care facilities and confined spaces (prisons).
  • Depending on jurisdictional testing capacity, case investigations may be considered for patients with a probable diagnosis of COVID-19, not just confirmed COVID-19 cases.
  • Broad community engagement is needed to foster an understanding and acceptance of local case investigation and contact tracing efforts within each community.
  • Significant social support may be necessary to allow clients with probable and confirmed COVID-19 diagnoses to safely self-isolate and close contacts to safely self-quarantine.
  • Due to the magnitude of the pandemic, jurisdictions will likely need to build up their workforce, recruit from new applicant pools, and train individuals from varied backgrounds.
  • The use of digital contact tracing tools may help with certain case investigation and contact tracing activities but will not replace the need for a large public health workforce.
  • At this time, if you have been vaccinated for COVID-19, you should follow existing CDC guidance on when and how long to self-isolate if you have COVID-19 or self-quarantine if you are a close contact. CDC continues to closely monitor the evolving science for information that would warrant changes to the recommendations for quarantine of close contacts.​

Case investigation is the identification and investigation of patients with confirmed and probable diagnoses of COVID-19, and contact tracing is the subsequent identification, monitoring, and support of their contacts who have been exposed to, and possibly infected with, the virus. Prompt identification, voluntary quarantine (hereinafter referred to as self-quarantine in this document unless otherwise noted), and monitoring of these COVID-19 contacts can effectively break the chain of disease transmission and prevent further spread of the virus in a community. While case investigation and contact tracing for COVID-19 may be new, health departments and frontline public health professionals who perform these activities have experience conducting these activities for tuberculosis, sexually transmitted infections, HIV, and other infectious diseases. Case investigation and contact tracing are well-honed skills that adapt easily to new public health demands and are effective tools to slow the spread of COVID-19 in a community.

This guidance aims to provide a foundation for state, territorial, local, and tribal development of case investigation and contact tracing plans. It is important to note that COVID-19 case investigation and contact tracing activities will vary based on the level of community transmission, characteristics of the community and their populations, and the local capacity to implement case investigation, contact tracing, and COVID-19 testing.

*Investigation in this context refers to a public health/infectious disease investigation and should in no way be interpreted as a criminal investigation.