Contact tracing

Coronavirus disease (COVID-19):
Contact tracing
28 July 2020 | Q&A

What is contact tracing?
Contact tracing is the process of identifying, assessing, and managing people who have been exposed to a disease to prevent onward transmission. These people are called contacts. Contact tracing for COVID-19 requires identifying people who may have been exposed to SARS-CoV-2, the virus that causes COVID-19, and following them daily for 14 days.

The goal is to stop transmission of the virus by reducing the number of people who are circulating with the virus.


How does contact tracing work?
Contact tracing is a process that includes several steps:
    Defining contacts: a contact is a person who has been exposed to someone else infected with the virus that causes COVID-19, from 2 days before to 14 days after the person started to show symptoms.

    Identifying contacts: this is done through an interview with the person infected with the virus that causes COVID-19 to find out who they have been in contact with.

    Informing contacts: each contact should be contacted by phone or in person to determine if they meet the definition and then be monitored. Each person confirmed as a contact should be informed about the goal of contact tracing, the process (including how their personal data will be protected) and who to contact with any concerns or questions.

    Additional essential information should be provided on how and when to quarantine, symptoms to look for, and what to do if the person becomes unwell.

    Managing and monitoring contacts daily: the contact person identified should be encouraged and supported to stay in quarantine, which means to separate from others in order to limit the possibility of exposing other people to infection should they become ill. During the quarantine period, daily monitoring should be implemented to monitor their health for any sign of illness. The monitoring ends 14 days after the person was last in contact with the person infected with the virus that causes COVID-19.

    Data processes and analysis: The information on each contact person is gathered in a database and updated daily monitoring on the person’s health status. These processes vary from country to country. See question What should be considered for data protection?



Who is defined as a contact?
A contact is defined as anyone who had direct contact or was within 1 metre for at least 15 minutes with a person infected with the virus that causes COVID-19, even if the person with the confirmed infection did not have symptoms. Contacts should remain in self-quarantine during the 14-day monitoring period to limit the possibility of exposing other people to infection should they become ill.



Can contact tracing help in controlling spread of the virus?
Yes, when systematically applied, contact tracing will break the chains of transmission, meaning that the virus transmission can be stopped. Contact tracing is thus an essential public health tool for controlling infectious disease outbreaks, such as COVID-19.



When should contact tracing be implemented?
Comprehensive contact tracing should be implemented as soon as cases or clusters are identified. During intense transmission, contact tracing may be difficult but should be carried out as much as possible, focusing on vulnerable and household contacts, healthcare workers and high-risk closed settings (e.g., dormitories, institutions, long-term care homes and other long-term facilities).

When countries have passed a peak in transmission and the numbers of sick people are decreasing, particularly when stringent public health and social measures are being adjusted, it is critical to maintain rapid identification of sick people and contact tracing. This identification and investigation break new transmission chains.



What happens if you are a contact?
If you are a possible contact, you should first be contacted by phone or in person by health authorities to determine if you meet the contact definition, which is anyone who has had direct contact or was within 1 metre for at least 15 minutes with a person infected with COVID-19. If you are confirmed as a contact, you will then be encouraged and supported to be in quarantine, which means to separate yourself from others, and to monitor your health for any signs of illness. The monitoring ends 14 days you were last into contact with the person infected with COVID-19.

By participating in contact tracing, you are contributing to controlling spread of the virus that causes COVID-19 in your area; vulnerable people will be protected, and more restrictive measures, such as general stay-at-home orders, might be avoided or minimized. This is an act of solidarity for your community.


Who is needed for successful contact tracing?
Everyone is needed for successful contact tracing and contact tracing begins with engaged communities. It requires individuals to agree to daily monitoring, to be willing to report signs or symptoms of COVID-19 promptly, and be prepared to go into quarantine for at least 14 days, or into isolation if they become symptomatic. Transmission of the virus that causes COVID-19 can only be stopped if we all play our role to protect our family, friends and community.

Contact tracing is only possible with contact tracers trained in the basics of virus transmission, prevention and control measures, how to monitor signs and symptoms, as well as the ethics of public health surveillance and quarantine. Ideally, contact tracers are recruited from their own community, including local government, civil society and non-governmental organizations, university students and community volunteers.


What are the tools used for contact tracing?
Contact tracing is carried out by people who are assigned and trained to carry out this essential activity to break the chains of transmission. Electronic tools and information technology are not essential for contact tracing but can help to make it more efficient and are useful if contact tracing needs to be done on a large scale. Many digital tools have been developed to assist with COVID-19 contact tracing and case identification. These should not be considered as single solutions for contact tracing, but rather as complementary tools and should be carefully identified and analysed for technical, cost, and ethical issues.

The Go.Data software application, for example, has been designed to support contact tracing and surveillance in outbreaks such as Ebola virus disease. Other tools exist for self-reporting of symptoms by contacts, as well as proximity applications that track people’s movements to indicate potential exposures to and from other persons.

More on contact tracing in the context of COVID-19: https://www.who.int/publications/i/item/WHO-2019-nCoV-Contact_Tracing-Tools_Annex-2020.1


What should be considered for data protection?
The ethics of public health information, data protection, and data privacy must be considered at all levels of contact tracing activities, in all training activities for contact tracing, and when using contact tracing tools. In particular:

    Safeguards must be in place to guarantee privacy and data protection in accordance with the legal frameworks of the countries where systems are implemented.

    Everyone involved in contact tracing must adhere to the ethical principles of handling personal information, to ensure responsible data management and respect for privacy throughout the process.

    How data will be handled, stored, and used needs to be communicated to those concerned in a clear and transparent manner. This is important for buy-in and engagement as well as to avoid misperceptions that could jeopardize the effectiveness of a contact tracing programme.

    Digital tools used for contact tracing should be assessed before use to ensure safeguarding data protection according to national regulations.