RALEIGH, N.C. (WNCN) — The counties across North Carolina with the highest full COVID-19 vaccination rates so far have populations that overwhelmingly rank either among the oldest in the state or have high per capita numbers of doctors or nurses, a CBS17.com data analysis found.

While obvious on the surface, the numbers put the trend into clearer perspective entering the third month of the massive vaccine rollout across the state.

There are a total of 25 counties where more than 5.5 percent of their residents have received both doses, according to a CBS17.com analysis of state Department of Health and Human Services data updated Tuesday.

Of those, 21 rank in the state’s upper quartile in at least one of several key measures — highest median age, percent older than 65, or the number of doctors, registered nurses or licensed practical nurses for every 10,000 people.

That includes Orange County, where nearly 9 percent of residents have had their second dose — only Pasquotank County, at 9.4 percent, ranks higher. Orange County also has the most doctors and registered nurses per capita in the state, according to employment data from the University of North Carolina’s Sheps Health Workforce N.C. and population projections for 2021 from the Office of State Budget and Management.

Groups currently eligible for the vaccine include health care workers or people older than 65.

“UNC Health, the hospital in Chapel Hill, is a big operation,” said Todd McGee, a spokesman for Orange County. “It has thousands of employees, so of course there’s lots of employees that work there and with that hospital, so they’re eligible.”

The trend is also evident in Durham County, with the second-highest number of doctors and nurses, has fully vaccinated 6.9 percent of its residents. Moore County, which has 7 percent of its population fully vaccinated, has the state’s 10th-highest median age (46.7), ranks 15th with 27 percent of its population over 65 and is in the top 10 in all three health care per capita rates.

Fourteen of the 25 counties with the highest rates rank in the upper quartile of at least one of the two age measures, with 10 ranking that high in the per capita number of doctors and nurses. Three counties — Pasquotank, Orange and Moore — rank that high in both age and health care-professional metrics.

Scotland County has the lowest percentage of its population fully vaccinated, just 1.8 percent. It has a median age of 39.7 with 19.3 percent of its residents over 65, making it one of the state’s younger counties.

There’s an even wider range among the counties whose residents have had their first dose. Chowan County leads the state with 25 percent having received at least one shot while in Hoke County, one dose has been administered to just 6.2 percent of people. Hoke County has a median age of 33.6 and just 10.6 percent of its population is over 65, the second smallest in the state.

“What we’re hoping to find out is where is vaccination happening, where is it maybe falling behind the rest of the state?” said Paul Delamater, a professor at UNC and a health geographer whose website — nc-covid.org — tracks several COVID-19 spread and vaccination trends.