‘Hola, Señor Diaz?”

I wait patiently as my interpreter introduces us, explaining that I work for the public health department in Arlington County, Va. But before I have a chance to speak, the man on the other end responds in rapid Spanish. “He was expecting you and knows why you’re calling,” the interpreter relays.

I’m not surprised: Most of the people who have been potentially exposed to the coronavirus already know. Usually, they are told by the person who tested positive, but once in a while, our call is how people learn about their exposure. The news can catch them off guard, making the interviewers’ jobs delicate — balancing a scared contact’s emotions while protecting the personal information of whomever they were exposed to, a legal mandate under federal health privacy laws.

As jurisdictions around the country attempt to open back up, contact tracing can help mitigate the spread of the coronavirus causing the pandemic. An NPR report this month found that states plan to put more than 66,000 workers on contact tracing duty. Public health departments like mine identify people who may have come into contact with an infected person, then notify them and tell them if they need to stay at home, or how they can continue working while reducing the spread of the disease. Otherwise, overwhelming outbreaks may force communities to adopt strict strategies — like infrastructure closures, stay-at-home orders, mandatory masks and enforced social distancing — again.

On the phone, I confirm Diaz’s information and verify the last time he remembers being in close contact with the positive case — defined as spending at least a few minutes within six feet. Since a person can transmit the virus before the onset of symptoms, we try to determine whom infected people may have interacted with in the 48 hours before they started to feel ill. In this case, Diaz’s uncle had covid-19, and Diaz had last seen him four days before, when he drove him to the hospital for a coronavirus test. I ask if he’s having any symptoms himself. Since he is an essential employee — a construction worker — he can return to his job without waiting for the recommended 14 days of self-quarantine, per the Centers for Disease Control and Prevention, under certain conditions: He must be symptom-free, wear a mask while working, practice social distancing on site, disinfect his work tools and area, monitor himself daily for any symptoms, and return home immediately if he starts feeling sick.

Diaz tells me he is unable to self-quarantine at home because he’s required to work, and besides, his family relies on his income. We hear this a lot from critical infrastructure workers, such as those with jobs at construction sites, convenience stores or farms, or in janitorial services. I read him the CDC’s guidance on safety practices he should implement at work and hope he is one of the lucky ones who doesn’t get sick.

We had gotten Diaz’s name and contact information during an interview with his uncle. Health departments receive reports of positive cases from labs, health-care providers and other health departments. Once a case is identified, we attempt to call each person to determine their contacts. Most of the time, people are forthcoming with information about who lives with them or whom they may have unwittingly exposed.

We do encounter occasional obstacles. First, positive cases must answer their phones — a challenge, given the number of people who do not pick up calls from unknown numbers. In those instances, we leave a brief message stating that the health department is calling about an urgent public health issue. Most of those we reach cooperate.

But not everyone is easily persuaded. On one call, a mother reported that her child had played soccer with his neighborhood friends (during Virginia’s statewide quarantine order) before he became symptomatic and tested positive. The mother declined to provide the names of the families who were exposed. She explained that she personally notified those neighbors herself, and that she didn’t have contact numbers for everyone and felt uncomfortable sharing them with us. Sometimes, people won’t tell us whom they live with, saying they want to protect family members’ privacy. Only rarely do people refuse to share any information, usually by avoiding our calls or by hanging up abruptly. Most people thank us for helping fight the pandemic.

We also face the unique challenge of calling people who are already hospitalized. At that point, we’re either getting secondhand information (through family members or nurses) or waiting until the patient recovers enough to talk. In rare but dire scenarios, interviewers have found positive cases who are having so much difficulty talking or breathing that they must stop the interview to call 911.

Since contact tracing takes a significant number of staff members, we are broken into teams, each conducting a different step in the process — calling people under investigation, calling their close contacts, keeping tabs on infected people we know about, identifying health-care workers who have been exposed, and monitoring hospitals, long-term-care centers, shelters and other public facilities for potential outbreaks.

In March, when everyone was still going about their normal lives, a colleague noticed that it was difficult for some people to remember their potential contacts: Most people were going to work, church, school, and events such as birthday parties and St. Patrick’s Day celebrations, and mundane interactions didn’t stand out. People were still traveling out of state, flying in and out of the area for business meetings and family vacations. Once Virginia was placed under a statewide stay-at-home order on March 30, it became easier for cases to remember whom they’d interacted with and when.

During one of my earliest calls, I listened as a nurse recounted the morning she initiated CPR on a nonresponsive elderly client at a skilled nursing facility who had symptoms consistent with covid-19 but had yet to be tested. The nurse immediately began chest compressions without any protective equipment, a maneuver that increased her risk of infection. When an emergency medical team arrived in full protective outfits to take the patient to the hospital, the nurse realized she was the only person not wearing the right gear. On a more recent call, I talked with a nurse who brushed a patient’s teeth and fed him when he had no symptoms, only to find out days later that he tested positive for the virus. Luckily for her, she was wearing proper protective equipment.

As a public health nurse, I’m proud of my department and the important work we do. Contact tracing is a labor- and time-intensive activity that requires skilled and compassionate interviewers and interpreters. And while much of our staff has gone virtual, we’re all still working diligently, contacting hundreds of people a day. As of Thursday, there were 1,763 cases and 89 covid-19-related deaths in our county, and more than 85,000 cases and 3,670 deaths in the D.C. region.

On my last call for the day after working on Diaz’s case, I reach a house cleaner and single mother of three young children who was recently infected. My interpreter and I wait to ask questions in between her coughs, giving her a moment to catch her breath. She reports feeling feverish and having chills, and her voice cracks when she mentions that her father and sister are hospitalized because of the disease.

“Is someone able to help you with the kids?” I ask hesitantly, knowing the worry and burden she must be facing.

Luckily, her mother was able to come over, allowing the woman to isolate herself. We talked about symptoms she would need to monitor and warning signs that would require a hospital visit or a 911 call. At the end, she thanked our department for this work. It’s our job. But keeping our neighbors safe is also what keeps public health workers going.

Twitter: @munn_jackie