Jennifer Conary looks away as she receives a COVID-19 vaccination, Wednesday, May 12, 2021, in Auburn, Maine. Credit: Robert F. Bukaty / AP

Maine continues to see large geographic differences in COVID-19 vaccinations even as more than 50 percent of the state’s total population and nearly 63 percent of eligible Mainers aged 12 and older have received at least one vaccine dose.

New zip code-level vaccination data, updated by Gov. Janet Mills’ office on Monday, shows the zip codes with the highest rates are concentrated in southern and coastal Maine. Of the more than 50 zip codes that have seen at least 80 percent of populations receive at least one dose, all but four — Hallowell, Stratton, Stoneham and Caratunk — are in coastal counties.

On the flip side, more than a dozen zip codes concentrated in Aroostook and Washington counties as well as rural areas in Penobscot County, have seen less than 40 percent of their populations get a vaccine dose so far.

Among the zip codes that represent Maine’s most populous cities and towns, wealthy zip codes in Cumberland County have the highest vaccination rates, with Yarmouth, Falmouth, Scarborough and Cape Elizabeth having the highest rates among zip codes with a population of at least 6,000. Lebanon and Berwick in York County have the lowest vaccination rates of zip codes with at least that population, at 39 percent and 42 percent respectively.

The estimates for the percent of each zip code’s population vaccinated are based on 2018 population totals, according to the Maine Center for Disease Control and Prevention, so towns that have gained or lost population since then could have slightly skewed estimates.

The effects of population changes would be muted in more populous zip codes, but may explain why a handful of zip codes — including Ogunquit, Bailey Island, Cliff Island and Prospect Harbor — show vaccination rates as high as 99 percent. Those zip codes likely still have high vaccination rates, but marginal increases in their adult populations during the pandemic may lead the data to overstate those rates.