Walgreens spaced Pfizer COVID-19 vaccines 28 days apart instead of recommended 21 days

Walgreens, one of the nation’s largest pharmacy chains, has helped administer the millions of COVID-19 doses developed by Pfizer-BioNTech. But the company has been administering the Pfizer’s two-dose shot 28 days apart, rather than the 21-day window recommended by U.S. health officials.

After complaints, the company will now update its scheduling system. 

By default, the vaccine-scheduling system that Walgreens uses books all second doses four weeks after the first. Walgreens said in a statement that it has done this "to ensure that no dose is administered earlier than the authorized intervals and patients are able to complete the series vaccination."

In many states, Walgreens stores administer multiple COVID-19 vaccines simultaneously, as determined by federal and state allocation. This includes Moderna’s COVID-19 vaccine, which is intended to be given four weeks apart.

Dr. Kevin Ban, Walgreens’s chief medical officer, told the New York Times that using the same spacing gap for both Pfizer and Moderna was "the easiest way to stand up the process based on our capabilities at the time."

After some customers began expressing concern over the 28-day window, the U.S. Centers for Disease Control and Prevention said in a statement that it was aware of Walgreens’ default four-week interval and said it "has asked the pharmacy partner to address the issue."

"For individuals who received the Pfizer COVID-19 vaccine, CDC continues to recommend getting the second shot 3 weeks (or 21 days) after the first shot, and to stick as close as possible to that recommended 3-week interval," the agency added in a statement.


FILE - A pharmacist prepares a Pfizer COVID-19 vaccine at The New Jewish Home long-term care facility on Manhattans Upper West Side in New York on Dec. 21, 2020.

Walgreens confirmed in its own statement on Monday that it will change its vaccine-scheduling system as soon as this week.

"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," Walgreens said.

The CDC says that the second dose of both the Pfizer and Moderna vaccines should be given as close to the recommended interval as possible, and also, "not earlier than recommended."

"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 on its website. 

But it also notes that currently, "only limited data are available on efficacy of mRNA COVID-19 vaccines administered beyond this window."

Data on the Pfizer vaccine from large clinical trials was based on the 21-day schedule, which found it to be 95% effective at preventing COVID-19.

Walgreens is one of many chains participating in the federal government’s national retail pharmacy program, which is helping to increase access to vaccines. Last week, the White House announced the program is expanding from 17,000 locations to nearly 40,000 across the country.

Walgreens reported last week that it had administered more than 8 million COVID-19 vaccines to date, including 4 million during the month of March.

In February, Dr. Anthony Fauci said the U.S. would "go by the science" from its own clinical trials and continue administering second doses of the Pfizer-BioNTech and Moderna vaccines within the recommended timeframe. The nation’s top infectious disease expert gave the remarks amid the U.K. implementing a contentious strategy of delaying the second shot so it can protect more people quickly with a first dose.

"We also are going very much by the data and science that has emanated out of very large clinical trials," Fauci said in February. "We feel strongly that we will go by the science, which dictated for us the optimal way for us to get the 94-to-95 percent response."

This story was reported from Cincinnati.