‘Contact tracing’ is the process of identifying, assessing, and managing people who have been exposed to a disease to prevent onward transmission. When systematically applied, contact tracing will break the chains of transmission of the disease and is an essential public health tool for controlling the spread of a virus.
Contact tracing generally involves the following steps:
- An individual is identified as having a communicable disease (often called the index case). This case may be reported to public health or managed by the primary health care provider.
- The index case is interviewed to learn about their movements, whom they have been in close contact with or who their sexual partners have been.
- Depending on the disease and the context of the infection, family members, health care providers, and anyone else who may have knowledge of the case’s contacts may also be interviewed.
- Once contacts are identified, public health workers contact them to offer counselling, screening, and/or treatment.
- Contacts may be isolated or excluded if deemed necessary for disease control.
- If contacts are not individually identifiable (e.g. members of the public who attended the same location), broader communications may be issued, like media advisories.
Contact tracing has been a pillar of communicable disease control in public health for decades. The eradication of smallpox, for example, was achieved not by herd immunity, but by exhaustive contact tracing to find all infected persons. This was followed by isolation of infected individuals and immunisation of the surrounding community and contacts at-risk of contracting smallpox.
In cases of diseases of uncertain infectious potential, contact tracing is also sometimes performed to learn about disease characteristics, including infectiousness.
NHS – Testing and tracing for coronavirus https://www.nhs.uk/conditions/coronavirus-covid-19/testing-and-tracing/nhs-test-and-trace-if-youve-been-in-contact-with-a-person-who-has-coronavirus/
Mayo Clinic – Contact tracing and COVID-19: What is it and how does it work? https://www.mayoclinic.org/diseases-conditions/coronavirus/expert-answers/covid-19-contact-tracing/faq-20488330
World Health Organization – Q&A: Contact tracing for COVID-19 https://www.who.int/news-room/q-a-detail/q-a-contact-tracing-for-covid-19
Centers for Disease Control and Prevention – Contact Tracing for COVID-19 https://www.cdc.gov/coronavirus/2019-ncov/php/contact-tracing/contact-tracing-plan/contact-tracing.html
Written by Eva Gozlan. She is currently validating her Master’s degree in Translation and International Communication at ISIT School.