Black people make up a disproportionate share of the population in 22 percent of U.S. counties, and those localities account for more than half of coronavirus cases and nearly 60 percent of deaths, a national study by an AIDS research group found.

The study also found that socioeconomic factors such as employment status and access to health care were better predictors of infection and death rates than underlying health conditions.

Gregorio Millett, vice president of Amfar, the Foundation for Aids Research, said the findings suggest that black people will be more vulnerable to the pandemic as states begin to reopen businesses and public spaces.

“It’s clear that there’s a disproportionate impact of covid-19 diagnoses and deaths among African Americans,” Millett said, adding that the authors of the study released it early in the hope of influencing policy decisions about reopening businesses. “All of my colleagues fear that with these policies to open up communities, that the brunt of the covid-19 epidemic is not going to be borne equally on all communities, that we will likely see greater covid-19 deaths as well as cases in African American communities.”

Millett said researchers plan to track disproportionately black counties in four states — Georgia, Texas, Alabama and South Carolina — to see what effect loosening social distancing and sheltering requirements will have on covid-19 cases and deaths.

Researchers at Amfar and the Rollins School of Public Health at Emory University in Georgia led the study team, which included investigators from Johns Hopkins, the University of Mississippi, Georgetown University and the nonprofit PATH.

The study adds to a growing body of data that has shown that black people have been infected and killed at disproportionate rates by the novel coronavirus. It also raises concern, as have other studies and analyses, about gaps in data collected and reported by county, state and federal officials about the race and ethnicity of virus sufferers, including testing, cases, hospitalizations and deaths.

The Amfar study, based on data collected April 13, focused on counties in which black people made up more than 13 percent of the population. Disproportionately black counties account for 22 percent of all U.S. counties but have been home to 52 percent of coronavirus cases and 58 percent of deaths from covid-19, the disease the virus causes.

Almost all disproportionately black counties have had at least one person diagnosed with the coronavirus, compared with 80 percent of other counties, and nearly half of counties with large black populations, 49 percent, have had at least one person die of covid-19, the study found. The higher diagnoses were found in disproportionately black counties in urban, small metro and rural areas. Death rates were higher in smaller metro areas and rural communities.

The study compared 677 disproportionately black counties in the country with 2,565 other counties. As of April 13, the United States had recorded 547,390 cases of covid-19 and 21,634 deaths. The Centers for Disease Control and Prevention acknowledges “a disproportionate burden of illness and death” among people of color. The agency is still criticized by civil rights groups for providing incomplete information about race and ethnicity for covid-19 cases and deaths.

Although public health experts and political leaders have attributed the high rate of serious illness and deaths from covid-19 among black Americans to underlying health conditions, such as heart disease and diabetes, the Amfar study found that those factors were not the primary cause of the disparities. Rather, other social determinants, including employment, access to health insurance and medical care and poor air and water quality, were more predictive of infection and death from covid-19.

Millett, a former scientist with the CDC who focused on racial disparities in HIV infections, argues that it is “structural issues that are placing African Americans at greater risk for not only covid-19, but multiple health conditions that we still have not adequately addressed as a society.”

The study noted that disproportionately black counties with higher unemployment actually had fewer coronavirus cases. It also noted that “black Americans are more likely to have jobs that increase exposure to covid-19, including jobs deemed ‘essential’ during the current public health emergency.”

The study also pointed out that 91 percent of disproportionately black counties are in the South, where many states have not expanded Medicaid under the Affordable Care Act, leaving low-income adults without health insurance. Rural communities in the South also have fewer medical professionals and facilities.

Even if elected leaders in these states are unwilling to immediately expand Medicaid, Millett said, there are “intermediate steps” that can be taken, including expanding testing in black communities, to improve prevention and treatment. He said officials also should take steps to reduce the populations of people in prisons and jails, which also have shown to be hot spots for covid-19.

Millett said that despite the disproportionate impact on communities of color, officials should remember that infectious diseases don’t respect geographical boundaries.

“Just because communities of color are disproportionately getting covid-19 or dying from it doesn’t mean it’s not going to affect other communities. Even though we live in a segregated society, people move around fairly freely,” he said.