Strategic COVID-19 Pandemic Committee 

What is contact tracing and why is it important?

COVID-19 Questions & Myths

Contact tracing is a strategy to reduce transmission of many infectious diseases by identifying exposed people who may be infected and notifying them to quarantine themselves and get tested. The steps in contact tracing are: 

  1. Identify and test potential cases based on symptoms or exposures. COVID-19 can start with fairly minor symptoms (with any combination of symptoms like tiredness, achiness, headache, gastrointestinal issues as well as cough, fever, shortness of breath, lack of smell and taste).

  2. Patients who test positive are asked about their contacts and places of possible exposure over the two weeks before onset (exposure information). As people can be infectious before they are ill, they are also asked who they have been in contact with and where they have been for two days prior to having symptoms until being questioned. (transmission information)

  3. The original positive patient is required to go into isolation while they are infectious to ensure that they can no longer transmit infection.

  4. The transmission information (where and to whom the positive person may have transmitted infection) is used to identify their contacts, who are at risk of developing infection at any time over the two weeks after the contact (on average, at five days after contact). The close contacts of the original positive patient are required to go into quarantine to ensure that they do not transmit the disease to others while developing symptoms.

  5. The exposure information (to whom and where they were originally exposed) from all cases is combined to look for patterns that could show a high-risk location (e.g., bar, church, grocery store, or event).

COVID-19 spread to household members is usually about 20% but can be reduced by avoiding common spaces, masking, distancing and handwashing. Support for a place to stay to protect the household is available if this is not possible. If very sick, people should be checked to see if they need oxygen or other therapy.

As long as contact tracing has enough resources to keep up with the number of new cases, it is a very effective way of reducing spread and ending outbreaks. Information about where, how, when, and to whom transmission is occurring is crucial in guiding other control strategies.