Supplies of the updated COVID-19 vaccine are still limited more than a month after federal regulators approved the new formulation, frustrating people who want to receive the shot but are having trouble getting an appointment.

People looking for immunization appointments may need “patience and persistence,” said Lindsay Hammes, a spokesperson for the Maine Center for Disease Control and Prevention.

“The Maine CDC is working with local, state and federal partners to address challenges with vaccine availability to help improve access so everyone 6 months and older can get vaccinated,” Hammes said. “Though it may, at this time, require patience and persistence, the Maine CDC encourages everyone who is eligible to seek vaccination this season, as it remains the best way to protect against the worst health impacts of COVID-19.”

The vaccines, made by Pfizer and Moderna and given the final approval on Sept. 12, are designed to combat the XBB.1.5 strain and other similar subvariants of the coronavirus that are currently circulating. Another vaccine made by Novavax was approved by the FDA in early October and also is being distributed. The vaccines reduce the risk of hospitalization, death and chronic symptoms known as long COVID.

Demand for the new vaccine is steady but not overwhelming, according to pharmacists in Maine. State and federal governments stopped tracking how many people were getting COVID-19 vaccines earlier this year. However, the U.S. Department of Health and Human Services has said that more than 7 million Americans got the shot in the first month after approval, based on reports from providers. That is similar to the rate of vaccinations after last year’s vaccine rollout. About 20% of American adults ended up getting the previous round of vaccines.

Supplies began coming in to pharmacies and doctor’s offices in late September, and it’s not clear why the supply is still constrained.

Amelia Arnold, pharmacy operations manager for Community Pharmacies, a Maine-based chain that includes pharmacies in Gorham and Saco, said it may have to do with a more fragmented distribution system.

“There’s been a lot of hiccups and bumps in the road,” Arnold said. The pharmacies have received thousands of doses, but still have not received about one-third of the shipment they initially ordered in July, anticipating federal approval.

Arnold said before this year, they ordered COVID-19 vaccine doses through the U.S. CDC, and it was a more streamlined and centralized operation. Now, they order from several private distributors, and the system is less predictable and consistent at delivering doses.

“Sometimes it’s gotten frustrating. It’s been a tough fall,” Arnold said.

Mike Blanchette, a CVS spokesman, said those seeking the COVID-19 vaccine should check cvs.com for vaccine availability, which can change quickly. He said CVS is “well positioned” to have enough supplies of the new COVID-19 vaccine for this fall.

Other places to look for vaccine appointments include Walgreens, Hannaford pharmacies and at your doctor’s office. Also, vaccine clinics can be found at AgeWiseMaine.

The latest vaccine rollout also led to frustrations last month when some people were incorrectly told the shots weren’t covered by their insurance plans and that they had to pay fees of as much as $200.

COVID-19 hospitalizations in Maine have remained relatively flat since late August, hovering around 50 patients hospitalized with the virus per day.