Walgreens has been scheduling second doses of both the Pfizer and Moderna vaccines at four-week intervals, despite the fact that, per the CDC, the suggested interval between Pfizer doses is three weeks, while Moderna’s is four weeks. These time frames are based on how the vaccines were administered in their respective clinical trials.ae0fcc31ae342fd3a1346ebb1f342fcb The reason why Walgreens had been administering the Pfizer vaccine one week longer than the suggested time frame was because it made the company’s vaccine planning process easier, Kevin Ban, MD, Walgreens chief medical officer, told The New York Times. By default, Walgreens’ vaccine-scheduling system booked all second doses four weeks after the first shot. (Meanwhile, according to The Times, CVS and Rite Aid stuck with the CDC’s distinct recommend timing for second doses of Moderna versus Pfizer.) “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,” Rebekah Pajak, a Walgreens spokesperson, said in a statement to USA Today. According to the CDC’s guidelines, “The second dose of Pfizer-BioNTech and Moderna vaccines should be administered as close to the recommended interval as possible, but not earlier than recommended (i.e., 3 weeks [Pfizer-BioNTech] or 1 month [Moderna]).” And for more on the differences between the vaccines, check out The One Side Effect That’s Much More Common With Pfizer, Data Shows. Now, complaints from customers and the CDC prompted Walgreens to change the way it administers the Pfizer vaccine, The Times reported on April 5. A CDC spokeswoman Kate Grusich told the news outlet that Walgreens has been asked to put a stop to its “longer-than-recommended” dose intervals. Walgreens is working to change their scheduling system to allow the three-week period to be implemented, Pajak told USA Today, adding that the change will be put into practice as early as the end of this week. And for more up-to-date COVID information, sign up for our daily newsletter. Despite the push for Walgreens to change its vaccination timing with Pfizer, the CDC has said it isn’t harmful for the second COVID vaccine dose (of either Pfizer or Moderna) to be administered as late as six weeks after the first shot. Although it’s not the ideal time frame, it is acceptable, the nation’s health protection agency explains. “If it is not feasible to adhere to the recommended interval and a delay in vaccination is unavoidable, the second dose of Pfizer-BioNTech and Moderna COVID-19 vaccines may be administered up to 6 weeks (42 days) after the first dose,” the CDC says. The agency adds that there’s “limited data” available on the effectiveness of two-dose vaccines given beyond a six-week interval. And for more on what to expect after dose No. 2, check out These Side Effects Are Much More Likely After Your Second Shot, CDC Says. Lawrence Gostin, a law professor at Georgetown University, told The Times, “It is not the role of a private, for-profit company to make public health decisions that should be determined by guidelines issued by a public health authority.” Meanwhile, Dima Qato, PharmD, a pharmacist in California, added, “As we’re trying to build trust in this pandemic, I think this may push us back.” However, Katherine Poehling, MD, a pediatrician who also spoke with The Times, feels Walgreens took a “very reasonable approach” to scheduling second vaccine doses of the Pfizer vaccine. “It’s a week difference. Everybody’s going to need to put it in their contexts and their risk factors,” Poehling explained. And for more on the vaccine that can keep you safe from all the new forms of COVID, check out This One Vaccine May Protect You Against All Variants, New Study Says.