Dania Palanker and her 7-year-old daughter, Nadia, felt excited as they bundled into the car in Washington last week to get Nadia’s coronavirus vaccine.

The evening before, Palanker received an automated email from Walgreens confirming Nadia’s appointment at the chain’s outlet in Cheverly, Md. “We’ll see you tomorrow!” read the subject line.

Their anticipation turned to disappointment once they arrived for the 6:30 p.m. shot. The store was still open, but the pharmacists had left, the pharmacy counter was closed and no one could provide vaccines. The pharmacy shuttered a half-hour before Nadia’s confirmed appointment, part of service cutbacks by Walgreens caused by a labor shortage hitting drugstores across the country.

“She was stoic,” Palanker said of her daughter. “I was furious.” Later that evening, she said, Nadia “looked close to tears.” Palanker went back online and found a city-run District of Columbia walk-up vaccination site, where Nadia got her shot the next day.

Walgreens apologized to affected customers in an email to The Washington Post and said it was working to prevent such problems moving forward. The company would not say how many of its customers nationwide have suffered the same frustration. Similar tales from angry consumers have popped up on social media around the country since early November.

The problems arose as demand is surging for coronavirus vaccine boosters as well as pediatric vaccine doses. President Biden’s administration has authorized boosters for everyone over 18 and is urging everyone to get the additional shot in response to the spread of the new omicron variant.

Palanker, a research professor and specialist on insurance and health care access at Georgetown’s Health Policy Institute, said she was especially dismayed because of the broader implications of her experience. An unannounced vaccine cancellation for a child would have a bigger impact on a family with less work flexibility or longer driving distances.

“My whole takeaway is Walgreens really dropped the ball,” Palanker said.

Walgreens is not alone among national chain pharmacies suffering from staff shortages. CVS said in September it was hiring 25,000 new workers at its stores, most of them pharmacists, pharmacy techs and nurses, to respond to heavy demand for coronavirus and flu vaccines and coronavirus tests.

But unlike rivals CVS and Rite Aid, Walgreens is attracting social media complaints from consumers about child vaccine appointments canceled without notice. Customers with appointments for booster shots and coronavirus tests also have complained on Twitter in recent days that they showed up to find closed Walgreens pharmacies.

Walgreens said it is working to improve its digital notification system to keeps up with local cuts in pharmacy service.

“We take this feedback seriously and are enhancing our digital scheduler to ensure it better supports fluctuations in store hours,” Walgreens spokeswoman Kelli Teno said in an email. “We apologize for any inconvenience to our customers and patients.”

Pharmacy operators have encountered the same pandemic-related workforce shortages as other health care providers and businesses, from retail stores to restaurants, said Scott Knoer, chief executive of the American Pharmacists Association, a professional education and advocacy organization based in Washington, D.C.

At the same time, demand for coronavirus testing and vaccines has increased the reliance on drugstores in the battle against the pandemic, he said.

“Pharmacists are having a tremendous amount of burnout right now,” he said.

As of Nov. 9, more than 162.8 million coronavirus vaccine doses have been administered by retail pharmacies in the United States, or about a third of all shots, according to the Centers for Disease Control and Prevention.

A shortage of pharmacists in the 1990s led to wage growth, but in more recent years there has been an oversupply, Knoer said. Then coronavirus suddenly boosted demand way beyond supply, sending chains into a struggle to fill jobs. ZipRecruiter and Glassdoor say pharmacists are paid between $100,000 and $150,000 a year. Walgreens in September announced bonuses of $1,250 for full-time pharmacists.

After the Food and Drug Administration on Oct. 29 authorized Pfizer coronavirus vaccine for children ages 5 through 11, the conflict between heavy demand from parents and surprise pharmacy closures created friction.

Anthony Funari, a grant professional and English professor at a community college in the Kansas City suburbs, had a confirmed vaccine appointment at a Walgreens in Olathe, Kan., for his sons, Will and Gabriel, on Nov. 11. He and his wife took time off from work and pulled the boys out of school shortly before their 10 a.m. appointments. The evening before, they had received the same cheerful appointment confirmation as Palanker.

“We were incredibly excited. This was the end of the pandemic for us in a way. We’d always been worried about our boys coming down with covid,” said Funari, whose story was first reported in the Kansas City Star in mid-November. When they arrived and learned from a store manager that the pharmacy was closed, Funari said he felt “disappointment, shock, frustration, anger.” His mother in law found a community pharmacy that could provide the shots later that day, he said.

In Homer, N.Y., Julie McChesney took her 10-year-old son, Zach, to his scheduled appointment at a Walgreens that was 25 minutes away from their home for a second vaccine shot. It was the Saturday after Thanksgiving. Once she found the pharmacy closed for the entire weekend, she and her son retreated to a Dunkin’ across the street, got some hot chocolate and hunted down another shot at a different Walgreens for later that day.

“I do wish somebody had let me know beforehand,” she said. “It would have been the right thing to do.”

Walgreens said it expects conditions to improve moving forward.

“We expect to resolve this quickly as we update the scheduler to accommodate fluctuating store hours and more appointments open up,” Teno said. “Beginning this Saturday, Dec. 4, we have 50% vaccine appointment capacity across all of our stores. The following week, Dec. 11, we have even more capacity, with nearly 70% of appointments available.”