Mike Cullen was surprised to receive an email Tuesday night that DeKalb County Board of Health had COVID-19 vaccination slots, and he quickly clicked on a link in the email to snag an appointment for the next day. He even got an email and text confirming he would get the shot at 9:50 a.m. Wednesday at the board’s drive-thru site at the Brandsmart USA parking lot in Doraville.

“I was thrilled to get it,” said Cullen, 71, of Brookhaven. “I was feeling like I was going to get my life back again. We haven’t been to a restaurant since March.”

But when he arrived Wednesday, something was off. As Cullen inched his car toward the front of the line, he noticed about every other vehicle was driving off without being directed to the vaccination tents. When he got to the front, a Georgia National Guardsman looked at the roster of appointments and told him he wasn’t on it.

“They said there was a system error,” Cullen said. “I was really mad.”

Cullen was not alone.

The board acknowledged Wednesday afternoon that it had a breakdown in its check-in process at the Dorvaille location that led to an untold number of people with appointments being turned away.

The problem occurred because the board had incomplete appointment lists, said Eric Nickens, the board’s spokesman.

He said DeKalb’s district health director, Dr. S. Elizabeth Ford, met with staff Wednesday to make sure the snafu doesn’t recur. Nickens said the board would reach out via email to those with appointments who were turned away to reschedule.

The breakdown comes as health boards and providers struggle to meet the overwhelming demand for the vaccine. Local boards’ websites and phone lines have been inundated since last week, when any Georgian 65 and older became eligible for the shots.

DeKalb has also been scrambling to shore up its appointment process after some people shared a general signup link on social media, which led to hundreds of people who were not registered signing up for appointments. A personalized link was sent to Cullen and others this week to try to avoid that problem. But Nickens said that hasn’t completely corrected it, and the board will be rolling out a revised signup process later this week or next.

“We definitely want to make sure people do this fairly and make sure they can’t circumvent the process,” he said.

Henry Cotten thought he and his wife, Marcia, were doing everything right when they received the board’s email Tuesday saying she was eligible for the vaccine. The Dunwoody couple, both in their 70s, signed her up and got email confirmation.

But when they got to the front of the line Wednesday, a guardsman told them Marcia wasn’t on the list and said they had to leave.

“This whole year has been that way — 2020,” he said. “You get kind of numb to it.”