EXPLAINER | What is Covid-19 contact tracing and how does it work? We ask an expert

Residents of Stjwetla Section in Alexandra township queue for Covid-19 swab tests outside a testing station on March 31, 2020.
Residents of Stjwetla Section in Alexandra township queue for Covid-19 swab tests outside a testing station on March 31, 2020.
Phill Magakoe, AFP

Contact tracing, when combined with physical distancing, has proven to be a powerful asset in controlling the spread of Covid-19.

But it is not a new method in combating disease. 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 universal immunisation, but by exhaustive contact tracing to find all infected persons, followed by isolation of infected individuals and immunisation of the surrounding community and contacts at risk of contracting smallpox. 

According to The Conversation, it is a powerful tool discovered almost a century ago to limit the spread of sexually transmitted infections from and to American troops.

It's a term we have become familiar with again since the outbreak of the novel coronavirus, but what does contact tracing entail and how is it carried out? 

News24 spoke to the Red Cross' George Mamabolo, the acting national programmes manager in charge of contact tracing, to find out how this essential tool is contributing to locating and isolating those who have been in contact with people who have tested positive for Covid-19. 

What is contact tracing?

Contact tracing is tracing and locating anyone who has been in contact with a Covid-19-positive person. These people may not necessarily know that they have been exposed to Covid-19, says Mamabolo. They, therefore, continue with their normal lives and could potentially unknowingly infect others. 

"It involves tracking down and tracing those who have had contact with those who have cases of the primary infection ('contacts')."

Because the symptoms of Covid-19 don't necessarily manifest immediately, it might take a while for an infected person to realise that they have been infected. During that time, they could have potentially spread the virus to a number of people, says Mamabolo. 

READ | Government to use cellphone towers to track all Covid-19 contacts

"What we do then is to look at the case definition in terms of the Department of Health's guidelines. We look at people who have been in contact with Covid-19. The person must have travelled abroad; have a fever; and display other symptoms - that is the case definition. 

"We need to then screen each possible contact, and we need to ask each contact to self-isolate. By self-isolating, you are reducing the spread, regardless of whether you have any symptoms yourself."

How is contact tracing done? 

The infected person is interviewed by a contact tracer to establish how many people they may have been in contact with and who those people are. In terms of international regulations, close contacts are those who have had face-to-face contact with a confirmed case for a period of more than 15 minutes, or those who have shared an enclosed space with a confirmed case for more than two hours.

This does not include people you may have encountered in a shop or passed in the street. 

According to Mamabolo, the identities of the infected person and the contacts are treated as confidential. 

ALSO READ | About 1 600 of Bloemfontein church gathering contacts traced – Mkhize

"The contact tracer will then get hold of the contacts through different means. They are then asked to come to a specified location to get screened. If they display any symptoms during screening, they are tested and told to self-isolate pending the results."

These contacts are then also asked about who they may have had close contact with, and the process is repeated. 

Mamabolo says contact tracing can become problematic if an infected person attended a large gathering or, say, travelled by bus, but in most cases the names of those people can be obtained. It does, however, make the process "voluminous".


 "We would then typically issue a notice asking people who have attended an affected gathering to come forward to be screened."

How are affected people contacted?

"There are different ways of reaching out, but most people are simply contacted by phone. There is no specialised technology that we use. Contact tracers make use of radio stations to reach people who may have attended gatherings, but in most cases it takes a phone call or text message. 

"The process of tracking must, however, incorporate personal distancing to reduce infection. We call people and send messages via SMS or WhatsApp, and follow those messages up with a phone call. 

Who works as contact tracers? 

"The Red Cross is a volunteer organisation," says Mamabolo. "The majority of the people who are part of the Red Cross are people who volunteer because they have certain skills, or who want to give back to their communities. People bring different skills and come from different backgrounds." 

How successful has the tracing process been in South Africa? 

Mamabolo says the process has been difficult, but communities throughout South Africa have been responding very well. 

"I'm not saying everybody responds, but overall we have seen an overwhelmingly positive response. South Africans are a very responsible community. People come with their families, others bring their husbands and wives or kids, or their grandparents, and so on. They are very responsive, regardless of different backgrounds or walks of life."

According to Mamabolo, people fear discrimination or stigma, and it is therefore important to talk about the virus to demystify it.  

"When you have the knowledge, you are able to save your life. You can also help to save the lives of those around you, as well as your family and your community.

Treat it with the seriousness it deserves, the pre

Stay at home

"We want South Africans to be responsive and responsible. Heed the president's call and stay at home. If you experience symptoms, pick up the phone and call the Covid-19 hotline. The virus knows no colour or gender or any boundaries. Whether you live in a shack or in the suburbs, you can be infected. 

"It is important for all of us to respond appropriately."

LIST | What complaints you can and cannot make against the police during the national lockdown

The number of people who tested positive for Covid-19 in South Africa currently stands at 1 462, which is an increase of 82 new cases, Health Minister Zweli Mkhize said on Thursday.

Of the new cases, 27 were in the Western Cape, 20 in KwaZulu-Natal, 18 in Gauteng, eight in the Free State, two in the Eastern Cape and Limpopo as well as one in Mpumalanga.

Four cases were still unallocated as it was not clear which province the people came from.

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