RALEIGH, N.C. (WNCN) – If you got the Pfizer vaccine at Walgreens, you may have noticed your doses scheduled four weeks apart even though CDC guidance recommends three weeks. The pharmacy chain will be changing that practice.

But what if you already got your shots?

Lisa May feels fortunate she’s had her first Pfizer dose. She’ll schedule her second as close to the CDC-recommended timeframe as possible.

“I would rather get it closer to the 21 days out,” she said.

People who schedule Walgreens appointments online have been automatically given a second appointment 28 days after the first dose, regardless of which vaccine they receive. Four weeks is the recommended interval for the Moderna vaccine. Pfizer’s is three weeks.

“We have worked closely with the CDC, federal, state and local government officials on COVID-19 vaccine distribution from the outset, and this includes recommended scheduling intervals for all vaccines.

In many states, our stores carry COVID-19 vaccines from multiple manufacturers simultaneously, as determined by federal and state allocation. The CDC states that second doses of Pfizer and Moderna COVID-19 vaccines may be administered up to 42 days after the first dose, but no earlier than the recommended interval of 21 and 28 days respectively. We have been automatically scheduling patients’ second doses to occur a minimum of 28 days following their first dose to ensure that no dose is administered earlier than the authorized intervals and patients are able to complete the series vaccination.

We’re continuing to work on system enhancements to our scheduler, and this week plan to have new functionality in place allowing people to schedule Pfizer second dose appointments within a three-week timeframe.”

Fraser Engerman, the Senior Director of External Relations for Walgreens

University of North Carolina infectious disease expert Dr. David Wohl said those who already received their Pfizer doses four weeks apart shouldn’t be concerned.

“No reason to be worried,” he said. “If it was me, I would not be worried about it. I think we know that the immune system is likely going to react three to four weeks after the first shot pretty much the same way. It’s just one company studied it at three weeks and one company studied it at four weeks and there’s a little bit of leeway.”

He went on to say people who haven’t yet received their second dose shouldn’t bother rescheduling the next dose.

“I really wouldn’t,” Wohl said. “I would worry more about making things too early. You’ve got to get that first dose and let your body react to it, let it calm down a little bit, and then hit it again.”

May is grateful she’s on her way to being to fully vaccinated.

“It definitely does bring me some comfort, you know, to have it done,” she said. She’s looking forward to dose two.

CBS 17 asked a spokesperson for Walgreens if the change will affect already scheduled appointments or just new appointments. Engerman said they’re looking into that.