More than a year and a half since the first COVID-19 vaccinations were administered in Maine, children as young as 6 months old can finally get their shots.

Last week, the U.S. Food and Drug Administration, followed by the Centers for Disease Control and Prevention, gave their final authorizations to begin administering the Pfizer and Moderna vaccinations in children 6 months of age and up to 5 years old, the last age group to get the greenlight.

The Pfizer and Moderna vaccines are a lower dose than the vaccines for older children and adults, according to the CDC. The Pfizer vaccine is authorized for children 6 months to 4 years of age and is a 3-dose series. The first two are given three weeks apart and the third, which is part of the primary vaccine series and not a booster, is given eight weeks later.

The Moderna vaccine is authorized for children 6 months old to 5 years old and is a 2-dose series administered four weeks apart.

As part of the preparation for the approval, the Maine CDC requested 24,400 doses — 12,200 doses each of the Pfizer and Moderna vaccines — for the first week of shipments. The state had finished delivering doses by Tuesday morning to about 40 health care networks and providers that had placed preorders, spokesperson Robert Long said Wednesday.

Long said the larger health care networks, such as MaineHealth, will use a “hub-and-spoke” distribution model, meaning they will distribute doses to individual providers and practices directly, rather than through the state.

“We ask that parents be patient with medical providers who are adding vaccination for this age group to their other work,” Long said in an email.

“Taking on this new work may create some early logistical challenges, but we’re confident that Maine’s medical community will rise to the occasion as they have throughout the pandemic,” he said.

Central Maine Healthcare, the parent company to Central Maine Medical Center in Lewiston and a primary care network that includes Central Maine Pediatrics, said it is offering the vaccine for young children during scheduled pediatric appointments, CMH spokesperson Jim Cyr said Wednesday.

CMH is working on setting up a weekend walk-in clinic but the details have yet to be announced, he said. More information will be posted on its website when they become available.

MaineHealth members Franklin Memorial Hospital in Farmington and Stephens Memorial Hospital in Norway and their associated pediatric practices are offering vaccinations through MaineHealth’s vaccine scheduling system. For more information, visit https://www.vaccine.mainehealth.org/.

A spokesperson for St. Mary’s Health, which includes St. Mary’s Regional Medical Center in Lewiston and operates Community Clinical Services on Birch Street in Lewiston, did not respond Wednesday to questions regarding appointment availability. According to Community Clinical Services’ website, CSS is offering primary doses and boosters every Saturday through the end of the year from 10 a.m. to 2 p.m. at B Street Health Center at 57 Birch St. For more information, visit https://www.communityclinicalservices.org/covid19vaccines or call 207-753-5400.

Pharmacies will receive doses through a separate program and are only allowed to vaccinate individuals 3 years and older, per federal regulations.

Long, from the Maine CDC, said that the state will continue to update the list of vaccination sites as it receives order requests from providers. To find a list of vaccination sites, visit https://www.maine.gov/covid19/vaccines/vaccination-sites or call the Community Vaccination Line at 1-888-445-4111.

This story was updated to clarify the federal vaccine authorization process and that the Maine CDC had completed deliveries to providers by Tuesday morning for the first week of pre-ordered doses.