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School of Public Health Expert Insights

contact tracing

An Inside Look at the Job of a Contact Tracer

Contact tracing is key to controlling COVID-19. Public health detectives are on the case.

By Jackie Powder | May 13, 2020


In the public health field, contact tracing is a tried and true method of connecting the dots between a person with an infectious disease and their close contacts.

The goal is to ask people with possible exposures to self-quarantine, reducing the risk of transmitting the disease to others and ultimately limit the spread of disease.

To that end, Johns Hopkins Bloomberg School of Public Health, with Bloomberg Philanthropies, launched the free online course “COVID-19 Contact Tracing” on May 11 to help train a large national workforce of contact tracers as some states and cities make moves to reopen.

International Health associate Tashrik Ahmed, PhD ’19, is part of the Bloomberg School group who developed the Coursera curriculum that teaches the fundamentals of contact tracing. The work isn’t purely academic for Ahmed, as he worked briefly on a health department contact tracing team.

In this Q&A, he provides an inside look at the job.

How does contact tracing work?

The process begins with talking to a person who has tested positive about their activities, getting basic demographics, asking questions about symptom history and any treatment they received, and ensuring they have the knowledge and resources to isolate. Then we put together a contact list and reach out to everyone that the positive case had been in close contact with.

This is a process that health departments are familiar with for STD and TB cases, for example, but the scale needed to contain COVID is unprecedented. It requires a lot of people and time to do properly, but when done correctly can be very effective in controlling disease transmission.

How do contact tracers start a case investigation and what types of questions do they ask?

For most jurisdictions, the names of positive cases are generated from lab reports that are sent to health departments.

We ask specific questions around high-risk, high-profile events: Have you had any travel? Have you been to a conference or meeting? Have you been to the movie theater? We start with the two days before symptom onset, and we go day-by-day, asking about their activities.

Asking people to remember their activities, which might be three or four weeks ago, is hard to do, so we help them walk through that process. It’s common for people to say "I didn't do anything yesterday," but when you start digging in—Where did you eat? How did you get there?—you find that they've been to three restaurants, visited two friends’ houses, and went to the dog park.

You said that some calls take 20 minutes and others can last for 3 hours. What might the conversation be like on a longer call?

It could be talking to people who have traveled to conferences, for example, or who went to a theater [and] then to a gala.

Then we would also get as much contact information as possible, asking questions like "Do you know who was in charge of the conference? Is there a number that we can call? Can you recollect if you sat at a specific table with certain people, and what their names are."

After you get off the call, you have to call up each one of those places and let them know that there was an exposure, so there's an additive effect every time they've been to a place.

Another complex scenario could be working through systematic barriers to isolation or quarantine with an individual who is homeless, and working with community services to make sure they get the care they need.

When a tracer has assembled a list of contacts, what’s the next step?

We notify [the contacts] that they've had exposure to a positive case. We do not identify who that person was, but we'd give them as much information as we can, letting them know, for example, that when they were at this particular place there was also someone who was positive. Often, they tell us that the person they were exposed to has already self-disclosed. That is what we encourage people to do once they know they’re positive—to reach out to their close contacts and let them know. That way, we're ahead of the game.

We ask contacts about signs and symptoms, but for COVID-19 they are so broad that they might not even understand or identify that they're symptomatic. If they have no signs and symptoms, we notify them what to look out for and how to safely seek care if they need to. Then we tell them exactly how long they need to quarantine.

How can a contact tracer offer support and guidance to someone whom they have just told to self quarantine?

We assess whether they need any help and what obstacles they might have. We might ask about their living arrangements, whether they share a bathroom and what steps to take to reduce transmission risk. We’d ask if they can get someone to bring them groceries or have food delivered if that’s an issue and walk them through that process. Then we let them know that there will be some sort of case follow up. Most health departments will call every other day or every few days to assess how people are doing.

Can you give a sense of the possible reactions tracers get when they contact people?

The average person tends to be very understanding. In the calls that I’ve handled, the vast majority of people are a little scared and have a lot of questions, but generally they're just happy that someone is checking in on them, that someone is asking about their medical status, and that someone is asking how they can help and what public services do you need.

The other common response is frustration, and it's completely understandable. We might be contacting them a week after they've had symptoms, because there's a delay between when they're symptomatic, when they seek care and get their tests taken, and when their test results get to us. Sometimes people were completely better by the time we were calling them and they're wondering, ‘Where were you when I actually needed some help?’

It's been rarer in my experience, but there are people who are just unwilling or unable to participate. Most of the time, they won't pick up the phone, and we're seeing higher rates of that right now. To some extent, I understand that. We're trying to get the message out that if you're sick, if you had a positive test, expect a phone call from the health department. It's important to take that call both for yourself and for your community.

What does it take to be a successful contact tracer?

You don't need to be a formally trained epidemiologist by any stretch of the imagination. In addition to some basic knowledge of how the disease is transmitted, what is really needed is the ability to understand and put yourself in that person's shoes, to be able to communicate with them and have them open up.

Active listening is number one. That is the paramount skill for a contact tracer, and curiosity is the second one. You have to be curious, you have to probe. You can't take the answers you're given at face value. Meticulousness is the third key skill. Someone who is very detail-oriented is a huge value to contact tracing.

A best practice is to have a contact tracer that's as close as possible to the community they’re interacting with. If the outbreak is among a Hispanic population, you should get contact tracers from that community. As part of the probing process, the contact tracer needs to understand cultures to ask the right questions. For example, right now is Ramadan. A culturally-aware contact tracer would be more likely to think to ask about iftar and fasting and going to prayer at night. A tracer without an understanding of the community can’t be expected to know that. You get more responsiveness from the people you're talking to if they're dealing with someone who is from their community and understands their context.

Jackie Powder is an assistant editor in the Communications & Marketing Office at the Johns Hopkins Bloomberg School of Public Health.