RALEIGH, N.C. (WNCN) — The gap continues to widen between North Carolina’s counties performing relatively well during the COVID-19 vaccine rollout and those that aren’t, a CBS17.com data analysis found.

The analysis uncovered several ways in which the performances of the counties have drifted further apart as the state moved deeper into the vaccination process — a problem potentially worsened by the increasing spread of the Delta variant.

“I don’t think it’s too much of a surprise, given the size of our state and its geography and other influences, that different counties are doing things differently,” said Dr. David Wohl, an infectious disease specialist at the University of North Carolina School of Medicine. “From east to west, north to south, we’re a pretty diverse state, and we’re not homogeneous. And we do know that there are counties where there’s just been a lot slower uptake of the vaccine. And some of those have been on the border with South Carolina, which would share some of the characteristics of those south of the border.”

It found greater separation between the county with the best vaccination rate — Orange County — and the one with the worst than there was in late May. Also continuing to grow: The gap between the top 20 counties and the bottom 20.

A total of 51.4 percent of all residents in the top 20 counties have had at least one shot as of Tuesday, compared to just 29.2 percent of those in the counties ranked Nos. 81-100. In other words, the top and bottom quartiles are separated by 22.2 percentage points.

The top 20 counties showed a rate of 48.8 percent in late May compared to 27.2 percent in the bottom 20 counties — for a separation of 21.6 points.

A study by Bloomberg News found a similar trend nationally, with the top and bottom quartiles of counties across the U.S. now separated by 32 percentage points — after that gap was 12 points in late March.

“We want to make sure that we’re raising vaccination rates consistently across the country,” Dr. Bechara Choucair, the White House’s vaccinations coordinator, told CBS 17 News.

The gap between Orange County — which led the state both last month and on Tuesday — and the last-place county also grew wider.

Orange County’s rate is nearly 43 percentage points greater than last-place Onslow County. Four weeks ago, Orange was 41.8 points better than Hoke County, which was in last place at the time.

The state says 45 percent of its total 10.5 million residents have gotten one shot to at least start the vaccination process.

And the analysis found both ends of the spectrum becoming more polarized.

There are seven counties — including Wake and Durham — where at least half of all residents have gotten a shot.

But in five counties — including Hoke, Harnett and Cumberland — their rates are stuck in the 20s. In Onslow and Hoke, it’s less than a quarter.

“There are discrepancies, but no one is hitting this out of the park,” Wohl said. “To the extent that we would love to see, you know, 80, 90 percent, we’re getting there. And I think we’ll get there slowly, too, I just think we should be realistic, no matter where you are, Orange County or elsewhere.”

The Delta variant makes it an even bigger issue because it spreads faster and is potentially more contagious than other strains, and a growing concern is that pockets of unvaccinated people could spark small clusters that could mushroom into big ones.

“Those places are at risk of having outbreaks and spikes, which means they’re at risk of having more hospitalizations or more lives lost,” Choucair said.

The key, of course, is reversing vaccine hesitancy. But a key question: How to persuade the holdouts who, months into the process, still have not yet come around to get the shots?

“I think having one-on-one conversations with trusted people is so important,” Choucair said. “What we learned from surveys, what we’ve learned from focus groups, is that people trust people they know — particularly, people trust their doctors. So having that one-on-one conversation with your primary care doctor is so important at this point.

“We’re encouraging (vaccinated people) to take a moment to share their experience with people they know, with their friends, that neighbor, their family who haven’t been yet vaccinated,” he continued. “And we know that they can make an impact. So it’s an all-hands-on-deck. We’re all rolling up our sleeves and trying to have these one-on-one conversations with people and we’re hoping more people will be vaccinated.”

CBS 17’s Joedy McCreary has been tracking COVID-19 figures since March 2020, compiling data from federal, state, and local sources to deliver a clear snapshot of what the coronavirus situation looks like now and what it could look like in the future.