Explanation: What is contact tracking and how can it help fight the new coronavirus?


(Reuters) – Contact tracing has been used for decades to control the spread of infectious diseases. The basic idea is simple: track down infected people, then find everyone nearby and encourage them to stay at home until it is clear that they are not sick.

FILE PHOTO: A computer image created by Nexu Science Communication in collaboration with Trinity College in Dublin, shows a structurally representative model of a betacoronavirus which is the type of virus linked to COVID-19, better known as coronavirus linked to Wuhan epidemic, shared with Reuters on February 18, 2020. NEXU Science Communication / via REUTERS

Currently, home stay controls are used worldwide to minimize the potential for spread of the virus infected with the new coronavirus. When the restrictions are lifted and normal activities resume, a thorough contact tracing will be necessary to prevent further epidemics.

Here’s what you need to know about contact tracing:


First, public health investigators discover everyone that an infected person has seen and wherever that person has gone in the past few days.

“Almost every infection has a period of time during which an infected person is considered contagious,” said Dr. Prathit Kulkarni, of Baylor College of Medicine in Houston. “Contact tracing is the process of determining who has been in sufficient contact with the person during the period that they were contagious to have been exposed.”

If investigators find people with symptoms, they can ask them to self-quarantine for two weeks and provide a contact list. People without symptoms can also be asked to quarantine and can be monitored to see if they have any symptoms.


While residence orders are in place, those infected do not come into contact with many others. In San Francisco, for example, each new case has only five contacts who need to be traced, said Dr. George Rutherford of the University of California at San Francisco, who works with the city to track people new coronavirus infections.

But once people go back to school and work, each person infected could easily come into contact with 1,000 others, he said.

“This is the first line of defense against the coronavirus once things have opened up again,” said Rutherford.


Hundreds of thousands of investigators will be required to conduct contact tracing in the United States once the stay orders are lifted, said Rutherford.

Some disease investigators already work in federal centers for disease control and prevention and in state and local health departments, but they account for only about one-tenth of the needs. The rest of the investigators could be a combination of recent graduates from public health programs, volunteers and librarians, or other government employees who have been on leave.

Extensive testing will also be necessary to identify those infected, said Dr. Ranu Dhillon of Brigham and Women’s Hospital and Harvard Medical School in Boston.

“Robust testing and contact tracing … will be essential to keep the COVID-19 transmission contained and get out of control again,” said Dhillon. COVID-19 is the respiratory disease caused by the coronavirus.

Report by Lisa Rapaport; edited by Nancy Lapid and Grant McCool

Our standards:Principles of the Thomson Reuters Trust.


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