Contact tracing is an essential public health measure and a critical component of comprehenssive strategies to contriol the spread of COVID-19. Contact tracing breaks the the chains of human-to-human transmission by identifying people exposed to confirmed cases, quarantining them, following up with them to ensure rapid isolation, and testing and treatment in case they adevelop symptoms
Identifying contacts
A contact is a person who has had any one of the following exposures to probable or confirmed case:
- Face to face contact with a probable or confirmed case within 1 meter and for at least 15 minutes;
- Direct physical contact with a probable or confirmed case;
- Direct care of a patient with probable or confirmed COVID-19 disease without the use of recommended PPE; or
- Other situations as indicated by local risk assessments.
Identifying contacts with different settings:
| Setting | Ways to identify contacts |
| Household contacts | Direct interview* with the SARS-CoV-2 case or their caregiver |
| Contacts in closed settings # | Direct* interview with the SARS-CoV-2 case or their caregiverList of residents, visitors and all staffs members working during the relevant timeframeSign-in sheetsMembership lists of gyms or other access-restricted facilitiesb Interview with coordinator or manager of facility |
| Healthcare settings | Identify all staff who have been in direct contact with the COVID-19 patient or who may have been within 1 meter of the COVID-19 patient without PPE for >15 minutes without direct contact by interviewing shift managers or reviewing rostersReview the list of patients hospitalized in the same room or sharing the same bathroomReview the list of visitors who has visited the patient or another patient in the same room during the relevant timeframeUndertake a local risk assessment to determine whether any additional exposures may be relevant, such as in common dining facilities |
| Professional contacts, including workplaces (other than healthcare settings) | Direct* interview with the SARS-CoV-2 case or their caregiver(s)Interview with facility managers |
| Public or shared transport | Contact identification is generally possible only where there is allocated seating Airlines and transport authorities should be contacted to obtain details of passengers and flight manifests. Passengers at highest risk will be those sitting within two rows of cases (in any direction), travel companions or persons providing care and crew members serving in the section of the aircraft where the case was seated. For public or shared transport where passenger lists or allocated seating is not available, a media release may be required to request passengers to self-identify. The media release may specify the date, time, pick-up location and destination and stops along the way, requesting people to self-identify as a potential contact. |
| Other well defined settings and gatherings (places of worship, schools, private social events, restaurants and other places serving food or drinks) | Undertake a local risk assessment and collaborate with organizers and leadership to notify potential contacts either actively or passively (for example, through media messages to an audience of possible attendees) Communication with focal points, such as faith leaders, about potential transmission events For private social events, work from guest registration and booking lists When necessary, consider media release specifying the event day and time, with request for people to self-identify as a potential contact For commercial settings, use registries of visitors where possible and consent-granted records For schools, conduct a risk assessment in the school with support from the school authorities. List possible high-risk contacts (e.g. close friends, classmates); follow up with family of confirmed cases to identify possible exposure |
*Can be virtual or in person using appropriate distancing, ventilation and PPE
# Long term living facilities, prisons, shelters, hostels, social settings, household settings other than the case’s home, gyms, meeting rooms, etc.
b In some cases it may be necessary to notify the entire membership that a SARS-CoV-2 infection has been identified and request potential contacts to self-identify to public health authorities or self-monitor for development of symptoms
Prioritizing contacts for follow-up
In scenarios where it may not be feasible to identify, monitor and quarantine all contacts, prioritization for follow-up should be given to:
1. contacts at a higher risk of SARS-CoV-2 infection based on their degree of exposure, with the goal of breaking chains of transmission; and
2. contacts at a higher risk of developing severe COVID-19 disease, to ensure early referral to healthcare. In general, proximity, duration and location of exposure determine the risk of transmission, although all contacts who meet the definitions above are at risk of infection
The following groups of contacts can be prioritized for identification, follow-up and support quarantine:
- Household contacts;
- Contactsmade in crowded or closed settings (longterm living facilities, prisons, shelters, hostels, social settings, household settings other than the case’s home, gyms, meeting rooms, etc.), especially in settings with poor ventilation. This can include ‘proximate contacts’ who were further than 1m away from a case but were in the same closed space for an extended amount of time without PPE;
- Contacts made during an index case’s period of greatest infectiousness (2 days before symptoms onset and up to 7 days after);
- Contacts made during an event or setting that has already led to other cases, identified through a case investigation.
Taken from WHO