Washington-area health officials are replenishing their ranks of contact tracers in hopes of curbing a recent rise in coronavirus infections that threatens to send the region back to widespread mask-wearing and other pandemic restrictions.

In June, when vaccine doses were widely available and the pandemic began to ebb in the region, local officials started to cut back on the numbers of workers assigned to track down contacts of a known patient and get them to get tested and keep their distance from others until they know they’re healthy.

Now, with new infections in the region at their highest point since early May, officials are rehiring those contact tracers or pulling them back from other assignments in anticipation of a continuing surge of infections ushered in by the highly transmissible delta variant of the virus.

“We’re making sure that we can meet the demand,” said Katherine Feldman, head of the contact tracing program for the Maryland Department of Health. “We’re asking people to work longer hours, to work additional shifts. We’re calling people back.”

Contact tracing has been vital to efforts to keep the virus under control, public health experts say.

The job entails finding the people who have been in proximity to a known patient and instructing them to self-quarantine, while also offering them guidance on symptoms to watch out for and any available government aid they may need.

When the pandemic started, contact tracers were hired by the thousands across the country as a line of defense as vital as wearing masks.

Contact tracing may be more important during the current surge in cases in terms of keeping local businesses open and allowing social activities to continue, said Crystal Watson, a senior scholar at the Johns Hopkins Bloomberg School of Public Health.

As of Friday, the seven-day average for new cases in the District, Maryland and Virginia stood at 1,306. That average was 199 on June 23, the lowest point since the start of the pandemic.

In response to the increased caseload, the District reimposed a mandate to wear masks indoors for everyone over the age of 2, vaccinated beginning Saturday. Other officials have said they are also eyeing a return to mask mandates.

“We want to keep moving forward and opening up and understand more about the delta variant and other variants of concern in the future,” Watson said. “Contact tracing is important, not only to limit transmission and keep incidents low, but also to gather information about how the virus is spreading.”

So far, the spike in cases is largely concentrated among area residents who are not vaccinated, with some breakthrough infections occurring with people who’ve received shots, local health officials said.

The relaxed restrictions in the region — where more people are eating at restaurants and going to gatherings of 10 or more — are also a factor, officials said.

In Virginia’s Loudoun County, a 30-fold increase in local infections — to a seven-day average of 32 cases Friday — is partly due to outbreaks occurring inside preschools and summer camps, where there are children younger than 12 who are not eligible for vaccination, said David Goodfriend, the county’s health director.

“We have a lot of folks who are just too young to be vaccinated, unfortunately, and we have a lot of vaccinated folks who live with those kids,” Goodfriend said, adding that his county also plans to beef up its ranks of contact tracers. “Part of the challenge is that, since the vaccine is so effective at preventing serious illness, folks who were infected and fully vaccinated never knew it because they didn’t have any symptoms.”

Those cases are where someone like Candace Haney comes in.

Haney works as a contact tracer for Loudoun, telephoning people who, typically unwittingly, were recently near a person whose test results for the virus came back positive.

During the year she’s done that work, Haney has been accused of lying about the potential exposure by some people she reached who were aggravated by the idea of having to miss work or time with their children to quarantine for 14 days.

Others have tried to grill her for information about the person who might have infected them — a detail that, under federal law, contact tracers are not allowed to provide.

Haney, 47, has also been a calm voice of reassurance, informing people about covid-19 symptoms, where they can get tested and any government aid — financial or otherwise — that might help them.

“I’m just trying to keep them safe and help them keep their families safe,” she said.

Public health officials anticipate that, given the highly transmissible nature of the delta variant, infections in the area will continue to rise, at least in the short term.

The delta variant, first detected in India, now accounts for more than 83 percent of new coronavirus cases circulating in the United States, the Centers for Disease Control and Prevention recently said.

With that expectation comes a need for more contact tracers and case investigators, a separate category of workers who interview people who’ve tested positive and ask them about places they’ve recently visited and the people they know they’ve been around.

Maryland’s contract tracers — who double as case investigators — work inside the state’s 24 local health departments or at a virtual call center staffed and managed by the National Opinion Research Center (NORC) at the University of Chicago.

At the peak of the pandemic, there were approximately 1,500 contact tracers in the state, more than half at NORC, Feldman said.

In June, NORC scaled down to between 75 and 80 contact tracers working each week while local health departments in Maryland did the same, she said.

For example, Montgomery County — Maryland’s largest jurisdiction — is down to 15 contact tracers from a high of 35, a health department spokesperson said. With the seven-day average for new infections up from single digits last month to 97 on Friday, the county plans to bring in more contact tracers, the spokesperson said.

In Virginia, a fifth of the state’s 1,055 contract tracers and case investigators have been reassigned to specialized units that focus on reducing transmission rates inside schools or local businesses, a state health department spokesperson said.

Those workers are still there. But the state’s 35 local health districts have adopted an accordionlike approach, scaling down when it’s quieter and expanding their ranks when cases increase, like now.

“The numbers are really dictated by the data and the trends that we see,” said Brian Hochstrasser, who heads a division in Fairfax County’s health department that has 80 contract tracers and case investigators, compared with 400 about five months ago.

D.C. health department officials said the District has had 150 contact tracers working throughout the pandemic and said that number is sufficient to handle the most recent surge.

Watson, the expert at the Johns Hopkins Bloomberg School of Public Health, said success in contact tracing requires reaching as many people as possible to limit the spread.

Generally, it has been difficult to get everyone who is potentially infected to respond to a contact tracer’s phone call or agree to an interview, officials said. The success rate for an interview in Maryland and Virginia is about 67 percent.

The challenge can be even greater amid the current surge if there are enough people exhausted by the notion of yet another spike, making them less inclined to cooperate, Watson said.

“It really depends on buy-in from the political level, the public health agency level and within the public,” Watson said. “If any of those is weak, it makes the job much more difficult.”