Walgreens is shifting its Pfizer COVID-19 vaccination scheduling after federal health officials noted the pharmacy chain quietly decided to space doses apart over a longer-than-recommended period, according to a report.

Federal guidelines call for the two-dose series to be administered at least 21 days apart, but Walgreens pushed the spacing to four weeks for easier logistics, the New York Times reports.

Second shots should be given "as close to the recommended interval as possible," the Centers for Diease Control and Prevention (CDC) advises, though the federal agency says the interval can be pushed up to six weeks apart. 


CDC spokeswoman Kate Grusich reportedly said the agency requested Walgreens stop using the extended dosing interval, however. 

The company’s chief medical officer, Dr. Kevin Ban, said that Walgreens aligned the four week-dosing intervals with vaccines developed by Moderna, also administered at the pharmacy chain, and Ban said it was "the easiest way to stand up the process based on our capabilities at the time," the newspaper wrote. The prolonged interval reportedly left some customers confused.

"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," Walgreens spokesman Jim Cohn wrote in part in a statement to Fox News.

Walgreens has administered over 8 million COVID-19 vaccines, and will adjust its scheduler to allow people to arrange Pfizer second dose appointments "within a three-week timeframe" this week, Cohn wrote.


Fox News has requested additional comments from the CDC.

"Pfizer and BioNTech’s Phase 3 study for the COVID-19 vaccine was designed to evaluate the vaccine’s safety and efficacy following a 2-dose schedule, separated by 21 days," Pfizer wrote in a statement shared with Fox News. "The safety and efficacy of the vaccine has not been evaluated on different dosing schedules as the majority of trial participants received the second dose within the window specified in the study design."

Pfizer also said it was "critical" health officials "conduct surveillance efforts on any alternative schedules implemented and to ensure each recipient is afforded the maximum possible protection, which means immunization with two doses of the vaccine."

Top officials at the Food and Drug Administration (FDA) have previously advised the public to adhere to the authorized dosing and vaccination schedules: two doses 21 days apart for Pfizer/BioNTech COVID-19 vaccine and two doses 28 days apart for the Moderna COVID-19 vaccine. That statement surfaced after reports that the U.S. FDA was in talks with Moderna and Operation Warp Speed officials to consider halving vaccines’ dose volume to speed inoculations and extend the supply.


"At this time, suggesting changes to the FDA-authorized dosing or schedules of these vaccines is premature and not rooted solidly in the available evidence," reads the statement. "Without appropriate data supporting such changes in vaccine administration, we run a significant risk of placing public health at risk, undermining the historic vaccination efforts to protect the population from COVID-19."