Dr. Sydney Sewall, right, instructs a volunteer while filling a syringe with the COVID-19 vaccine at the Augusta Armory, in this Tuesday, Dec. 21, 2021, file photo, in Augusta.  Credit: Robert F. Bukaty / AP

More than half of Maine’s COVID-19 deaths since the start of 2021 could have been prevented by broader uptake of vaccines and boosters, a new study found.

Maine still saw fewer “preventable” COVID-19 deaths than most states, according to researchers from Brown, Harvard and Microsoft AI for Health. Nationwide, they estimated there were roughly 318,000 vaccine-preventable deaths through the end of last month.

The estimates show how Maine’s high vaccination rate has substantially reduced virus deaths here, but they also suggest that greater uptake of both the original vaccine and boosters could have saved more lives. It comes at a time when Maine is seeing another resurgence of the virus, with hospitalizations as of Friday more than double the total from a month ago.

The researchers developed a counterfactual situation in which the peak rate of people getting newly vaccinated when vaccines were first rolled out in the spring of 2021 continued until all adults were vaccinated.

For Maine, they estimated that nearly 1,100 deaths could have been prevented by universal uptake of vaccines and similarly broad uptake of boosters in the fall of 2021. Even a 90 percent vaccination rate among adults — up from the current rate of roughly 82 percent — still would have saved more than 500 lives here, the researchers found.

The results were even more stark in other states. In West Virginia, which has a population about 30 percent larger than that of Maine, the estimates revealed that more than 3,300 deaths could have been prevented under the scenario where all eligible adults were vaccinated while more than 2,500 deaths could have been prevented under the 90 percent vaccination rate scenario. Just 57 percent of West Virginia adults are fully vaccinated.

Vaccinations substantially reduce individual risk of severe illness or death from COVID-19. A U.S. Centers for Disease Control and Prevention analysis using data from 23 states found people who are not vaccinated against COVID-19 were 10 times more likely to die from it in the month of February than people who were vaccinated, when adjusting for age.

People who got a booster shot saw their risk of death cut in half compared to those who only received the original vaccine course.

Boosters have garnered increased attention in recent months due to an uptick in COVID-19 deaths among vaccinated people due to waning immunity from the initial course of shots. Maine saw a surge in COVID-19 nursing home deaths this fall driven by outbreaks that began shortly before booster shots were approved for older Mainers, although the case fatality rate in long-term care facilities was still lower than prior to the vaccine rollout.

Nursing homes are now among the environments with the highest booster rates in Maine. Among nursing homes reporting data to Medicare as of early May, the median share of residents who were fully vaccinated was 96 percent, while the median share of vaccinated residents who were also boosted was 91 percent.

Although nursing home outbreaks in Maine have risen again in recent weeks as a highly contagious omicron variant is causing a surge in cases statewide, the state has not yet seen a large rise in deaths. Maine nursing homes have reported three total COVID-19 deaths in nursing homes in the past three weeks, after going five weeks with zero deaths, federal data show.

Overall, 78 percent of Mainers aged 65 and older who are fully vaccinated had received a booster shot as of last week, according to U.S. CDC data, compared to 60 percent of the overall adult population.