Role Of Contact Tracing In Controlling COVID-19

26 Mar 2020

As the number of coronavirus cases in India increases, authorities in different states are relying on contact tracing, a concept in epidemiology (the study of the distribution and determinants of health-related states or events).
The idea behind contact tracing is to stop the outbreak by breaking the transmission chains.

What is Contact Tracing?

It is defined as the identification and follow-up of persons who may have come into contact with an infected person.
It is an important part of epidemiologic investigation and active surveillance.
Contact tracing is not a novel concept and has been used as a method to track cases of the Ebola virus in Africa in 2014.

Who is a Contact?

Anyone who provided care for the suspect or confirmed case, including a health care worker (including those involved in cleaning, waste management, laboratory technicians, doctors) or family member, or anyone who had close physical contact; anyone who stayed at the same place (lived with, or visited).

Elements of Contact Tracing

According to WHO, contact tracing can be broken down into three steps:

Contact Identification

This involves identifying the contacts of the infected person by asking about the person’s activities and those of people around them since the onset of illness.
In the case of the first positive COVID-19 patient from Chandigarh for instance, a chain of 119 people was traced directly or indirectly to the patient.

Contact Listing

This means listing all those people who came in contact with the infected person.
Efforts should be made to identify every listed contact and to inform them of their contact status, what it means, the actions that will follow, and the importance of receiving early care if they develop symptoms.
In some areas across India, authorities are releasing lists of those who are quarantined and are identifying their houses by putting quarantine posters in front of their houses.

Contact Follow-Up

It involves regular follow-ups with all the contacts to monitor for symptoms and test for signs of infection.

Digital Contact Tracing

It’s a way to figure out if two people were in the same location at the same time, based on co-location tracking with the help of an app with a GPS-based location logger.
When a person is confirmed as having COVID-19, they donate their GPS data to the app’s server. This gives a location trail of everywhere they’ve been for the last two weeks, but without revealing the person’s identity.
Everyone else who uses the app can look at those trails to compare with their own to see if there was significant overlap, but they never have to share their trails.

Recent Example of Digital Contact Traciing

On 19^th March, 2020, the Government of Singapore launched a mobile app called TraceTogether, to help support and supplement current contact tracing efforts in the nation-state in an effort to reduce the spread of COVID-19.

How can Contact Tracing help in Controlling the Coronavirus Outbreak?

Since everyone has many contacts, contact tracing is useful when there are only a few cases.
At this point, in many countries, we have so many cases that everyone would be contacted. This is essentially the lockdown — everybody isolates.
According to the Lancet, the feasibility of controlling the COVID-19 outbreak by using isolation of cases and contacts to control 90 percent of the outbreaks, 80 percent of contacts needed to be traced and isolated.
However, while a fifth of the world’s population is currently isolated and under lockdown, it may not be feasible to trace contacts of all the infected patients given the scale of the current coronavirus outbreak, with over 4 lakh infected people.
Further, the study notes that in some scenarios, isolation alone would be unlikely to control the outbreak within a period of three months.

Conclusion

While contact tracing is an important step during a disease outbreak, it is insufficient alone in controlling it, requiring other interventions.
Rapid and effective contact tracing can reduce the initial number of cases, which would make the outbreak easier to control overall.
Effective contact tracing and isolation could contribute to reducing the overall size of an outbreak or bringing it under control over a longer time period.