In this March 3, 2021, file photo, senior citizens leave a COVID-19 vaccination site operated by Maine Health in the site of a former department store in Sanford, Maine. Credit: Robert F. Bukaty / AP

AUGUSTA, Maine — More than a dozen COVID-19 vaccination sites in Maine will offer doses without appointments next week in a rapid and marked shift from scarce doses and few appointments to little issue getting a shot as the vaccine effort continues.

The prevalence of walk-ins is striking because of how quickly it was adopted. Just over two weeks ago, Maine Center for Disease Control and Prevention Director Nirav Shah gingerly discussed the possibility of appointment-free clinics, warning they could come with logistical hurdles to ensure doses would not be wasted.

But five days later, Shah announced that the state’s mobile vaccination clinic would be offering walk-ins shots as it struggled to fill slots. Two days after that, he actively encouraged providers to try to provide the option. Previously, the only way to get a vaccine without an appointment in Maine was to be on a list maintained by providers to take wasted or leftover doses.

The shift suggests Maine is moving into a more relaxed phase of vaccinations as clinics see dwindling interest in rigid appointments. It may continue to shift more into smaller or clinical settings. Shah recently called appointment-free clinics “a model that meets the needs of Maine people where they are.”

“I don’t think it’s the model, but it’s a model,” he said last week.

The state itself has made a fast switch. At the state’s mobile clinic, which is part of a federal partnership, 60 percent of the mobile clinic’s doses have gone to walk-ups since the option began last week, said Maine CDC spokesperson Robert Long. Patient feedback has shown people were drawn to the clinic because of that option, Long said.

Maine’s two largest hospital systems — MaineHealth and Northern Light Health — began offering vaccines to walk-ins at limited locations this week. Spokespeople for both hospitals said they did not have data on the number of vaccinations administered to patients with appointments compared to those who showed up without. Both have announced plans to extend walk-ups appointments to some of their larger sites next week, including MaineHealth’s mass site at Scarborough Downs and the Northern Light site at the Cross Insurance Center in Bangor.

The majority of sites still require appointments, however, including Hannaford, Shaws and Walgreens pharmacies, which are Maine’s partners in a federal program and account for roughly half of vaccination sites statewide but are each relatively small.

The evolution of appointment-free vaccines was natural as those eager to be vaccinated are replaced by those who need more flexible options or are not in a rush, said Noah Nesin, the chief medical officer of Penobscot Community Health Care. Offering off-hours vaccines will probably be a next step in reaching working people or those with childcare challenges, he said.

Penobscot Community Health Care began offering walk-in appointments beginning at 7 a.m. last week, one effort to improve accessibility to Mainers who work during the day. Mid Coast Hospital in Brunswick is offering vaccinations as late as 7 p.m. on weeknights, while the Cross Insurance Center in Bangor will be open until 7:30 p.m. next Thursday.

The VA Maine Healthcare System did a trial run of walk-in clinics a few weeks ago to see if the option would work for patients, said spokesperson Jason Carter. It has now held three clinics where a veteran could walk or drive to a location and get a shot without an appointment.

Walk-ins have made up just 4 percent of the first doses the health system has administered in April, but Carter said the method is likely here to stay as immediate interest in getting vaccinated wanes.

“It’s slowing down but it’s not going away,” he said. “The interest is there.”