When it comes to battling the spread of the novel coronavirus, Kentucky and Rhode Island might look similar on paper. They’ve done comparable numbers of diagnostic tests and lost similar numbers of residents to the disease.

But there’s one key difference. Kentucky has more than four times Rhode Island’s population, meaning it has tested 0.7 percent of its residents, compared with Rhode Island’s 3.7 percent, the highest per capita testing level in the United States.

The difference suggests Rhode Island probably has a better sense of the virus’s spread throughout the state, making it better prepared to curb it.

The contrast offers a clear illustration of the challenges posed by a state-by-state testing strategy, in the absence of a national plan coordinated by the federal government.

The White House’s decision to delegate the responsibility for coronavirus testing to the states is starting to shape how those states can respond to the pandemic’s path, experts say. While some states with extensive health-care resources have made more progress in tracking the virus, others are struggling to catch up. And that discrepancy could become much more critical as restrictions are eased and officials try to determine who can return to work.

“This is what you get when you get a 50-state strategy on fighting a pandemic,” said Ashish Jha, director of Harvard’s Global Health Institute. “Pandemics affect all of us equally. We don’t have a country where every state is supposed to be self-sufficient on all issues related to pandemic preparedness.”

Rhode Island is not only a small state by population, but also by area. Barely more than 1,000 square miles, it has 13 hospitals, as well as the corporate headquarters of the nation’s largest pharmacy chain, CVS, a company that has been integral to its testing successes. CVS’s testing accounts for 40 percent of the state’s total.

“We just have a lot of health care relative to our size,” says Jeffrey Bratberg, a professor of pharmacy practice at the University of Rhode Island. “We only have a million people.”

By contrast, Kentucky has tried but could not get the same access to testing supplies and processing. It reserved its limited tests for those experiencing symptoms and front-line workers, hospitalizing 33 percent of its 3,050 confirmed cases and admitting 17 percent of them to intensive care units. These figures appear to be the highest hospitalization and ICU admission rates in the nation, based on partial data collected by the Covid Tracking Project, which has data from some states, but not others.

Kentucky Gov. Andy Beshear (D) mobilized early to confront the pandemic, restricting residents’ activities, coordinating with neighboring states and delivering daily briefings. But the state encountered problems early on getting access to diagnostic tests and personal protective equipment.

“One of the reasons that there is a high rate in Kentucky is because we have had limited testing,” the governor said at his briefing Monday evening. “And what we have done is we have prioritized it for those who are the sickest.”

Limited testing means Kentucky might be detecting only the most severe cases that need hospitalization and intensive care, which could help explain its high rates.

Beshear also said the state’s demographics play a role. Twenty-five percent of adults in Kentucky smoke, a rate second only to that of West Virginia, according to the Centers for Disease Control and Prevention. Smokers and those with other lung conditions are more vulnerable to the coronavirus. Kentucky also has the nation’s highest cancer rate and a high incidence of asthma, said Ben Chandler, president and CEO of the Foundation for a Healthy Kentucky.

“This disease attacks the lungs,” said Chandler, a former state attorney general and congressman.

Physicians in Kentucky have been quick to admit people who test positive for the coronavirus, and that that has pushed up hospitalization rates, Beshear said. “We believe that our doctors are being very proactive, which is really important,” he said.

Beshear has worked aggressively to expand his state’s testing capacity. Kentucky recently forged an agreement with the grocery store chain Kroger to provide drive-through testing, with a goal of conducting 20,000 tests over the next five weeks.

The tests, which will turn around results in about 48 hours, are reserved for health-care workers, first responders and people exhibiting significant symptoms, as well as those with milder symptoms but who have been exposed to someone with the virus.

Initially, Kentucky sent many tests out of state, which led to lengthy wait times for some results. One Louisville resident, who spoke on the condition of anonymity to discuss private health matters, said he and his wife were able to get tested through a doctor they knew in early March, after learning they had been exposed. But by the time he got the positive results back two weeks later, he had been hospitalized and put on a ventilator in the intensive care unit.

Gravity Diagnostics, based in Covington, Ky., is ramping up testing in the state, which health officials said will speed up results.

Nancy Galvagni, CEO of the Kentucky Hospital Association, said testing firms continue to prioritize supplies with states experiencing severe outbreaks, an ongoing challenge for her members. There are 155 Abbott Laboratories machines in the state that can run tests, she noted, but they need a software upgrade to process coronavirus tests that are being shipped to hot spots right now. Separately, the state received more than a dozen different Abbott machines to run the firm’s rapid tests — but they each need at least one test kit cartridge to validate the results. Those are in short supply.

“It’s a recurring theme,” said Galvagni, who added that she understood why other states rank higher in terms of their needs than Kentucky. “We’re not a hot spot. We get low priority on things.”

But without comprehensive testing on a nationwide scale, it will be hard for the United States to see or predict where the next severe outbreaks will occur, experts say.

Rhode Island had conducted 39,333 coronavirus tests as of Tuesday, compared with Kentucky’s 32,820. The small New England state has 171 fatalities from the disease, whereas Kentucky has 154. At the same time, Rhode Island has identified more coronavirus cases than Kentucky — 5,500, versus the latter’s 3,050.

With similar numbers of deaths, that means that the disease appears less severe in Rhode Island, where the current case fatality rate is only 3.1 percent, compared with Kentucky’s 5 percent. Part of that could stem from the fact that Kentucky may not have been able to identify as many of its less-severe coronavirus cases.

When it comes to coronavirus testing in Rhode Island, CVS has proved crucial. The company created a drive-up rapid testing site at a casino in Lincoln, R.I., which is using new technology from Abbott Laboratories to perform 1,000 tests daily.

It’s one of five such sites that CVS has across the country that can accommodate multiple lanes of traffic, according to the company.

“The combination of larger testing sites and on-the-spot test results has helped to maximize the efficiency and safety at these new sites, while helping the state prevent the spread of the virus,” said CVS spokesman Joseph Goode.

“As far as I know, if people want a test, they seem to get it,” Bratberg said of the situation in Rhode Island. “Two of my students got tested and had no problem obtaining the test.”

Rhode Island’s testing is expansive enough that anyone can be diagnosed, said Bratberg, but not yet broad enough to conduct surveillance to determine the extent of asymptomatic infections — people carrying the disease who can spread it. Still, compared with other states, Rhode Island is in a strong position, and it is still scaling up testing.

Other factors make things appear worse in Kentucky.

One-third of covid-19 fatalities have been in nursing homes, said Donna Arnett, dean of the College of Public Health at the University of Kentucky.

“We are a state that skews old, and skews sick,” Chandler said.

Sarah Moyer, who directs the Louisville Metro Department of Public Health and Wellness, said the state is trying to build up testing capacity so people can return to work, but has yet to reach that point.

“I wish we had more testing for essential workers right now. That’s where we would expand if we could,” Moyer said. “Going forward, we need to get that capacity up and going if we’re going to start to open up the economy.”