About 40 percent of adults in the U.S. have at least one underlying health condition that would put them at risk for severe complications of COVID-19, according to a report published Thursday by the Centers for Disease Control and Prevention.
Certain chronic health problems, such as obesity, Type 2 diabetes, kidney disease and cardiovascular disease, are known to be more prevalent among COVID-19 patients sick enough to be hospitalized. A study published in April found that among people hospitalized with COVID-19 in New York City, 57 percent had high blood pressure, 41 percent were obese and just over a third had diabetes.
Full coverage of the coronavirus outbreak
To determine the prevalence of those health conditions nationwide, the CDC authors used statistical modeling based on the 2018 Behavioral Risk Factor Surveillance System, a telephone survey of nearly 500,000 U.S. adults. The survey included data on people living in every county in the nation.
When the study authors looked at each county, they found wide health disparities in the rates of five chronic conditions: obesity, Type 2 diabetes, kidney disease, heart disease and chronic obstructive pulmonary disease. In some counties, about 1 in 4 people had at least one of those chronic conditions. That number rose to about 2 in 3 in other counties.
"Counties with the highest prevalences of any condition were concentrated in Southeastern states, particularly in Alabama, Arkansas, Kentucky, Louisiana, Mississippi, Tennessee and West Virginia, as well as some counties in Oklahoma, South Dakota, Texas and northern Michigan," the study authors wrote.
In general, the rates of chronic medical conditions were higher in rural areas.
Download the NBC News app for full coverage of the coronavirus outbreak
The granular county-by-county data presented in the CDC report can help guide public health officials at a local level.
"It will allow for more effective messaging about social distancing and other public health measures," said Dr. Dan Culver, a pulmonary and critical care physician at the Cleveland Clinic, adding the information could be used to make decisions on where to allocate supplies and therapeutics.
"Targeting the more vulnerable populations will be easier if we understand where they live," Culver said.
As of Thursday afternoon, the U.S. had tallied more than 4 million cases of COVID-19.
Follow NBC HEALTH on Twitter & Facebook.