At a press briefing last Monday, D.C. Mayor Muriel Bowser drew attention to two District neighborhoods that, official data showed, had strikingly high concentrations of coronavirus cases: Columbia Heights and 16th Street Heights, both located in Northwest. Two days later, the city for the first time released its collection of COVID-19 data by neighborhood, including an eye-catching map.

But the map, seemingly drawn with arbitrary borders, left Washingtonians with many questions about the actual incidence of COVID-19 cases throughout the city. For one thing, the underlying data are based on the number of positive cases confirmed by testing, which, while becoming generally more available, is still far from universal.

For another, some neighborhoods appear to be simply missing from the map, as they’re neither distinctly drawn or labelled. Dupont Circle is gone, Fort Totten looks like it’s hidden in what’s designated as Michigan Park, and Cleveland Park is absorbed by the area described as Woodley Park. (The precise boundaries of the city’s various neighborhoods may often be debated, but whether specific, named neighborhoods exist is usually less disputed.)

The numbers on the map refer to incidents of coronavirus cases, not percentages, and the data show that Columbia Heights leads the neighborhood rankings with 298 confirmed cases as of the map’s release. 16th Street Heights has 273 cases, Chinatown 249, and Brightwood 242. By comparison, Georgetown is listed as having only a dozen cases.

D.C. Health spokesperson Alison Reeves tells DCist that the neighborhood designations align with official census tracts. She adds that the map also roughly matches the 38 “neighborhood clusters” used by D.C.’s Office of Planning.

“Naming conventions were a combination of iterations that aim to capture most of the neighborhoods that D.C. residents are familiar with,” Reeves says in an email. “As actual neighborhoods may overlap and don’t fall within census tract lines, some familiar neighborhoods may not be included in the actual name of the D.C. Health Planning Neighborhoods.”

For example, Dupont Circle isn’t listed because it’s in the middle of four other neighborhood designations, according to D.C. Health: Adams Morgan, GWU (George Washington University), Georgetown East, and Logan Circle/Shaw. “While we recognize that neighborhoods are a mix of individual and community identity, they also serve a purpose in small-area estimates to show disparate outcomes of important health indicators,” says Reeves.

These neighborhood designations were also used two years ago as the basis for the D.C. Health Equity Report, which examined nine key health factors within 51 statistical neighborhoods. Since the report’s publication, the planning office and the health department have revised the boundaries on the map. Among the changes: Lincoln Park was included in Capitol Hill, and George Washington University and the National Mall were split into two separate neighborhoods.

The 2018 study found that only 20 percent of health disparities among District residents can be explained by “clinical factors,” like insurance rates and healthcare access. The other 80 percent is tied to what experts call “social determinants” of health, such as housing, employment, and food access.

The coronavirus pandemic has further exposed those disparities, as black residents make up less half of D.C.’s population, but 80 percent of COVID-19-related deaths to date. Although the neighborhood-level data reveal a wide variation in cases across predominately black Wards 7 and 8, the latter has seen the highest death toll from the virus throughout the District’s eight wards—at 61 of the 285 total fatalities recorded as of Thursday.

When pressed about why 16th Street Heights and Columbia Heights had seen such relatively high numbers of COVID-19 cases at Monday’s press conference, D.C. Health Director LaQuandra Nesbitt pointed to household transmission as a leading concern.

“We see these cases in high-density mixed-use corridors where the average number of individuals per household is higher than the city average,” she said. Nesbitt also said the “typical occupations in those neighborhoods are more related to the essential work that continues to happen,” such as construction and healthcare.

On Wednesday, Bowser said that ensuring physical isolation when someone contracts COVID-19 is crucial for preventing the disease from spreading. “If they can’t safely isolate in their home, then they need to reach out to us so that we can attempt to help them isolate,” the mayor said. “That way, we won’t see the cases expanding in households.” (The District is currently renting hundreds of hotel rooms where people who lack private isolation space, including homeless residents, can self-quarantine.)

The data released this week show that the coronavirus is hitting neighborhoods with high populations of Latino and black residents the hardest. The city’s Latino population has about 1,200 cases per 100,000 residents, while its black and white populations have 820 and 175 cases per 100,000 residents, respectively.

In an interview, Ward 1 Councilmember Brianne Nadeau, who represents Columbia Heights and its surrounding neighborhoods, says the data aren’t too surprising, in light of the large share of Latino residents in her ward. “We definitely want people to hear the message that there is no need to panic,” Nadeau says. “But we do need to take seriously our infection rates and do all of the things recommended by the health department tests to stay safe and to keep each other safe.”

New data on testing by ward are expected in the coming days. Some wonder if the high counts of cases in certain neighborhoods are related to more residents receiving testing in those areas.

Still, “Dr. Nesbitt has specifically said that based on the data available, they do not think it is simply due to an increase in testing, but that it’s a true increase in the number of cases in the area,” says Nadeau. “Whenever we see an increase, that’s always the first question we ask: Have we just been doing a better job of testing? And it seems to not be the case here.”

City officials have said they’re concerned about big households being unable to create enough distance within their homes when someone becomes infected with COVID-19 to curb transmission effectively. Complicating matters, many of the community clinics that residents in the most heavily impacted neighborhoods rely on are suffering economically because of the ongoing crisis.

A few weeks ago, the D.C. Council’s health committee held a briefing with primary care providers from Unity Health Care, Mary’s Center, La Clínica del Pueblo, and Community of Hope, according to Nadeau. The clinics reported facing steep financial losses.

Both Nadeau and Ward 4 Councilmember Brandon Todd, who represents 16th Street Heights, say it’s still too early to reopen the city fully and ease social-distancing guidance, given the current prevalence of COVID-19. Todd notes that the District is increasing its free testing capacity, which could help officials get a better handle on the scale of the outbreak.

“We have a testing site just at the line of Ward 4 at [UDC’s] Bertie Backus [campus] and they have the ability to test up to 500 people a day,” he says.