RALEIGH, N.C. (WNCN) — The North Carolina counties doing the best job at giving COVID-19 booster shots tend to be the ones that got the most residents vaccinated in the first place.

The state Department of Health and Human Services recently began breaking down their booster data by age and by county — after previously disclosing only the lump sum of those shots — and an analysis of that data turned up some clear patterns.

Only people 12 and older can even get the booster shots, so it makes sense to look at the rates for that age group. And while the numbers don’t reflect booster eligibility — five months after receiving either of the two mRNA vaccines, two months after the single-shot Johnson & Johnson one — they do give a rough idea of the winners and losers so far.

“It doesn’t quite tell us how many people were eligible to get that booster,” said Dr. Erica Pettigrew, a family practice physician and assistant professor at the University of North Carolina School of Medicine. “But it tells us that we we have some work to do to make sure that people who are eligible for their booster can go ahead and get it.”

Understanding the places doing the best and worst at giving boosters is important because they provide significantly increased protection against the omicron variant that is currently engulfing the state and the nation, leading to tens of thousands of new cases per day, record counts of hospitalized patients and rates of COVID tests confirming new cases in the 30s.

Pettigrew says the rate she’s watching is the share of fully vaccinated people who have gotten their booster. NCDHHS counts 5.8 million people 12 and older who are fully vaccinated, and just 44 percent of them have been boosted — though, again, some of those people aren’t able to get the booster until enough time passes since the initial vaccine series.

And those rates vary wildly between counties — from 59 percent of those in Chatham County, to just 20 percent in Onslow.

(This chart shows the booster rate — the percentage of fully vaccinated people 12 and older who have gotten a booster dose — for each of North Carolina’s counties. The counties shaded blue are the counties where two-thirds or more of people in that age group are fully vaccinated, while counties shaded red have vaccination rates below 50 percent.)

The state has 15 counties where at least two-thirds of their 12-and-older residents are fully vaccinated. Seven of them rank near the top when it comes to giving boosters, a list that includes three counties in central North Carolina:

Orange: 80 percent vaccination rate, 59 percent booster rate.

Durham: 77 percent vaccination rate, 53 percent booster rate.

Wake: 80 percent vaccination rate, 51 percent booster rate.

At the other extreme, there are 17 counties where fewer than half of their residents in that age group are fully vaccinated. Not surprisingly, nine also have some of the lowest booster rates — including two in the area.

Hoke: 40 percent vaccination rate, 36 percent booster rate.

Harnett: 46 percent vaccination rate, 38 percent booster rate.

“I think that in counties where you have people who had easy access to their primary series likely continue to have relatively easy access to boosters, and would be people who are valuing that extra layer of protection and so may be more motivated to go ahead and get it,” Pettigrew said.

But should that change the messaging around the boosters?

After all, the counties giving the fewest boosters tend to also be the ones giving the fewest shots as a whole.

“Especially in places where the overall vaccination rate is low, getting shots to people who have not gotten any are is still the top priority,” Pettigrew said.

“So we need to continue focusing on that gap so that those folks are really protected against severe illness and death.”