This story was last updated Aug. 19 at 2:48 p.m.

Over the past two months, as the region has continued its phased reopening plans, public health experts have reemphasized the need for contact tracing as a tool to limit the spread of the coronavirus. Nationally, some states have tripled their contact tracing workforce in a matter of weeks to meet the demand.

Contact tracing isn’t new: It has been used to contain other outbreaks like smallpox and SARS. Public health experts have repeatedly highlighted it as the key to stopping the spread of COVID-19 and responsibly reopening the economy. So, how does contact tracing actually work in the region? What are our local health departments learning from contact tracing, and has it been effective at stopping the spread of the coronavirus?

We contacted the health departments of the District, Maryland and Virginia to help answer some basic questions.

What happens when a contact tracer calls you?

The goal of contact tracers is to get in touch with people who have tested positive for COVID-19, as well as any person who came into close contact with them while they may have been contagious (the Centers for Disease Control defines “close contact” as being within six feet of an infected person for at least 15 minutes). Contact tracers then advise sick or potentially exposed people about how to isolate or quarantine so that they don’t enter the community and continue spreading the virus. Here’s a breakdown by jurisdiction of what contact tracers want to know and how they’re doing their jobs:

The District: A disease investigator of nearly two years, Malachi Stewart, told DCist/WAMU in May that contact tracing is a similar process no matter the virus.

“I’m going to be asking you questions about, you know, where have you been? How did you get home from work that day? Did you take the Metro? Did you take an Uber? These kind of questions,” Stewart said. “I want to hear about, you know, if you went to the grocery store, what time did you go? Did you have on the mask? Were you six feet apart from people?”

D.C.’s contact tracers follow up with people every five days by phone after the initial contact, according to D.C. Health spokesperson Alison Reeves.

Maryland: In Maryland, when contact tracers call, they verify your identity, confirm your preferred language, assure you that they will protect your privacy, and then launch into a series of questions about your activities over the previous two weeks.

Katherine Feldman, who leads the contact tracing effort at the Maryland Department of Health, says tracers also ask for your preferred mode of follow up: text, phone call, or email. A contact tracer will follow up with people who are sick every three days until they meet the state health department’s criteria for release from isolation. The patients’ close contacts get checked on every day until it has been 14 days since they were known to be exposed to the virus.

Virginia: Marshall Vogt, an epidemiologist who is helping coordinate the state’s contact tracing program, says he previously worked in infection prevention in CJW Hospital in Richmond, and that it is common to track sexually transmitted disease or whooping cough via contact tracing. “The principles are the same, it’s just I think the scale, the magnitude in which case investigation and contact tracing is occurring that makes it unique,” he says.

Contact tracers reach out to people who might have been exposed, advise them on the symptoms, and stress the importance of quarantine, Vogt says. The contact tracer will also refer the person to testing and to medical follow up if they have symptoms, and any additional services they need: “Do they need help getting groceries? Do they need help paying rent money because they won’t be able to be at work perhaps?”

Vogt says contact tracers enroll people in Sara Alert, a software system created by Mitre and in place in Virginia since late May. The software sends emails, texts or phone calls to patients to monitor their vital statistics. If people are not comfortable using Sara Alert, Vogt says contact tracers will arrange to call them daily to monitor symptoms. Monitoring lasts for 14 days from the last date of exposure, Vogt says.

Does the region have enough contact tracers, and is there enough capacity for a spike in cases?

The District: The Department of Health currently employs 300 contact tracers, which the department says is enough to meet the city’s need. Reeves of D.C. DOH says the department has the “capacity to scale up if needed.” That just might be necessary. Researchers at George Washington University put out a Contact Tracing Workforce Estimator, which uses daily case counts to estimate how many contact tracers are needed in various states and jurisdictions — and based on its latest estimate (as of Aug. 3), D.C. needs to hire at least 100 more people.

Maryland: The state has 1,350 contact tracers, which is just under a quarter of the staffing that GWU recommends. “We are certainly able to meet a surging demand,” says Feldman, who leads Maryland’s contact tracing effort. “In fact, a few weeks ago … when case counts did rise, we identified a need to surge, and we did.”

Virginia: The commonwealth has 1,902 people working as contact tracers and case investigators, according to Tammie Smith, a spokesperson for the Virginia Department of Health. Those include both contractors and full-time employees working at the state level and for the Fairfax and Arlington health departments. This figure is not close to the GWU estimator, which says Virginia needs nearly 6,500 contact tracers.

“We still have volunteers working for us … and we still have staff that may be nutritionists or environmental health staff that are working on contact tracing,” says Vogt, the contact tracing coordinator. He says the department is still hiring, both to free up reassigned staff and to prepare for a surge, and it is also working to sharpen its training and operations.

How many people are contact tracers interviewing?

The District: Unlike Maryland and Virginia’s health departments, D.C. doesn’t publicly list data on how many contacts are successfully reached. It only shows “attempts” to reach people on its COVID-19 tracker. The public page has shown little insight into what the process is like and how successful it is. But internally, D.C. Health is tracking how many people with positive tests it’s interviewing.

“We are completing interviews in roughly 60-65% of cases overall, though the number varies from day-to-day,” Reeves says, citing data as of July 15.

Maryland: Contact tracers in Maryland have successfully completed interviews for about 66% of the cases they have entered in their database. Currently, contact tracers are able to reach out to new cases within 24 hours about 85-90% of the time.

Public health officials across the state are encouraging residents to pick up the phone if they see “MD COVID” on the caller ID or get a call from 240-466-4488. “This is how we’re gonna stop disease transmission in Maryland,” Feldman of the Maryland health department says.

Virginia: Virginia publishes data weekly on the percentage of cases reached within 24 hours (this week it’s 85.3%) and on the number of contacts under monitoring (10,413 as of this week). Vogt, the contact tracing coordinator, estimates contact tracers reach out to between 10-20 people per day, although the number varies by case. VDH estimates that it’s unable to reach 18.4% of contacts to date.

What is the data telling us about how people might be getting the virus?

The District: D.C. contact tracers focus on two main things when calling people: activities in the two weeks prior to diagnosis when the virus could be incubating; and activities while actually infectious. Based on these efforts, health officials say that about 10% of people testing positive for the virus said they have traveled outside of D.C. within two weeks of their diagnosis. (D.C. now orders people to self-quarantine if returning from a running list of “high-risk” states.)

In addition, D.C. Health Director Dr. LaQuandra Nesbitt said at a July press briefing that an “increasing number” of people have dined in restaurants while they were infectious, and a number of contagious people have also worked outside their homes. In August, Nesbitt said about 5% to 8% of patients interviewed by contact tracers in D.C. reported dining out — and a “higher proportion” of cases seemed to be related to work or travel.

About 15% of people interviewed by contact tracers during a two-week period in August said they had attended a “large event” with more than five people, Nesbitt said. The vast majority said the events they attended were smaller than the 50-person limit allowed by city guidelines.

Maryland: The state health department is aggregating data about where people are working and the kinds of activities they are participating in. Feldman says that health care jobs were the most commonly-named profession among those who indicated they had been traveling outside their homes to work — 25% of these “essential workers” said they worked in health care. And 20% of people interviewed by contact tracers said they had gone to a gathering of 10 people or more. The remaining 80% either didn’t answer the question, said they didn’t know, refused to answer the question, or said they had not attended a gathering.

The most common type of social activity among those interviewed was family gatherings, followed by house parties, and outdoor events. Maryland is also collecting data on the kinds of businesses people have gone to, and says it will soon start asking people questions about their recent travel.

These answers don’t necessarily tell us exactly where people got the virus. “It’s really hard to dissect out which venue might have been the source,” says Feldman. “But it does give us great insight into the types of activities people are participating in, and it might help us direct where messaging should be.”

Virginia: Vogt at the Virginia Department of Health says people in Virginia are contracting the virus when they have been in COVID hotspots or to large indoor spaces where they could not socially distance. He says his data was not detailed enough to specify whether restaurants in particular are a vector, as D.C. has noticed, but he has seen trends of younger patients whereas earlier on, the cases were older patients living in nursing homes.

Anecdotally, Vogt says, “what’s really stood out to me are the people that know there is a risk of exposure but they go out anyway. They choose to go, again, to those places where it’s crowded, they’re not able to socially distance from folks. They may not be as concerned about COVID-19 and then wind up becoming ill … And I think that is a real wake up call.”

Are people actually complying with quarantine?

The District: While contact tracers ask about whether patients have been in isolation since they started experiencing symptoms, D.C. Health says it doesn’t have a summary of that data.

Maryland: “We don’t have any way to track compliance right now,” says Feldman. She has heard of another jurisdiction outside of the state that has been conducting “spot checks,” meaning they knock on people’s doors to check whether they are quarantining.

“That’s something we certainly could do,” says Feldman. Some public health departments, including the Virginia Department of Health, have also been experimenting with apps that notify people who were exposed to the virus. Feldman says “there could be a role for technology in helping monitor compliance,” but concerns about privacy mean that “it would need to be carefully thought through.”

Virginia: Vogt says he does not have data on the people who complied with orders to quarantine, but he believed most people were following the directions based on their own reporting. “We are not outside their doors watching their every move,” Vogt says.

Contact tracers check in with patients to understand if they need support to quarantine. Vogt says, “I think it becomes very apparent if someone is not complying.” The state health commissioner is authorized to issue orders of quarantine, although Vogt did not know how many orders have been issued.

How successful is contact tracing at tracking and preventing the spread of the virus?

The District: One key metric for measuring the success of contact tracing is the percentage of new cases that come from quarantined contacts. This metric, recommended by the Centers for Disease Control and Prevention, can tell local health departments the extent to which the spread of the virus is controlled and understood by contact tracers.

So far, D.C. is the only jurisdiction in the region tracking this number. The city’s data indicates that most people are still contracting the virus in the community, and most new cases are not surfacing among close contacts of sick people who are already in quarantine. As of Tuesday, just 2.9% of new cases in D.C. currently come from quarantined contacts. The city’s goal is for that number to rise to 60% or higher.

“Ideally, what we want to see is more of our cases connected to each other … and more of our cases occurring in clusters, meaning that we have more evidence of containment,” Nesbitt, the health director, said a press briefing last month.

Maryland: Feldman, with the Maryland health department, says the number of new cases coming from quarantined contacts of patients “is something we intend to track,” but she did not have a time estimate on when the state would start tracking and publicly sharing the data. Feldman says that this metric is “one of the ultimate outcome measures” for stopping transmission of COVID-19.

Virginia: Vogt says his office did not calculate the percentage of new cases found by contact tracing, although it is exploring using the Sara Alert app to understand the percentage of contacts who become infected.

Is language ever a barrier?

The District: Contact tracers receive cultural and linguistic competency training during a two-week on-boarding process, Reeves says. Additionally, the health department uses translation services to meet the requirements of D.C.’s Language Access Act.

“Sometimes working with the interpreter, that can be a bit of a challenge and it can sometimes make the interview take a little bit longer,” contact tracer Malachi Stewart told Washingtonian last month. “It’s a public service. You stay on the phone. You do what you have to do.”

Maryland: In Maryland, 60 of the state’s 1,350 contact tracers speak Spanish. Feldman says this is enough to offer contact tracing interviews in Spanish. The state also contracts with a translator service to conduct phone interviews in other languages.

For the approximately 15% of people who contact tracers speak with on the phone but do not interview, Feldman says, “sometimes there are language barriers, and we try to work with the individuals to address language needs.” Others do not complete interviews because they are not available and it proves difficult to reschedule, or because they refuse for other reasons.

Virginia: Of Virginia’s 1,902 contact tracers and case investigators, only 128 speak Spanish, per VDH spokesperson Smith. Latinx patients account for more than a quarter of all cases in the state. Smith says as of early August, 206 contact tracers and case investigators had skills in other languages, including Spanish. In June, the state health secretary Daniel Carey announced he aimed to have 20% of contact tracers be bilingual, but Virginia is still falling short.

Will contact tracers protect my privacy?

The District: D.C. Health says that investigators don’t reveal the identities of people who test positive to their contacts. Tracking and collecting coronavirus data is a sensitive process, so health workers try to be as personable as possible, which motivates people to open up more, says Stewart, the contact tracer.

“The integrity of how we handle protected health information is really important to us. It definitely won’t be shared,” Stewart told Washingtonian. “We’re not going to call people and say, hey, such-and-such at your job tested positive, you’ve been exposed, you need to go. That’s not how we do things. This is really a public health effort. We’re not using information to penalize people. There’s no judgment.”

Maryland: Maryland’s contact tracing website also emphasizes privacy, saying that contact tracers maintain strict adherence to HIPAA regulations and that the infected person’s name won’t be disclosed to their contacts.

“We want to assure anyone that when contact tracers call, they take extreme measures to protect the privacy of the individuals with whom they’re speaking, whether it’s cases or contacts,” says Feldman. “All of the contact tracers go through training so they understand the implications and they understand what they need to do.”

Virginia: Vogt, says patient privacy is paramount: “When we’re talking to the case and they’re giving us contacts, and then we’re contacting those individuals who may have been exposed, we’re saying, ‘you were potentially exposed to somebody who had COVID-19’ but we’re not naming who that person is.”

This story has been updated with additional information from D.C. Health about contact tracing interview responses.