A pharmacist administers a dose of the Pfizer-BioNTech Covid-19 vaccine to a resident of a nursing home in the Bronx neighborhood of New York on December 21.
Photographer: Eric Lee / Bloomberg
Photographer: Eric Lee / Bloomberg
Pfizer Inc. said that the second dose of its Covid-19 vaccine should be administered to individuals within the recommended 21-day period, calling into question a UK decision to space the dosing regimen.
The UK’s decision not to retain any of its vaccine supplies is aimed at reaching as many high-risk people as quickly as possible. According to the government plan, second doses could be administered up to 12 weeks later, more than the three-week time determined as ideal by Pfizer’s final stage studies and the four weeks suggested for the injection developed by Moderna Inc.
People should be vaccinated at the recommended time, he told Pfizer on Thursday, warning “there is no data to show that protection after the first dose is maintained after 21 days”.
Information about efficacy around a single dose has been misinterpreted, said Peter Marks, director of the US Food and Drug Administration office that oversees vaccines. Having a shot, he said, “is worrying.”
“If people don’t really know how protective a vaccine is,” said Marks in an e-mail, “there is the potential for danger, because they can assume they are fully protected when they are not and change their behavior to take unnecessary risks. “
Marks’ comments come as The British Medical Association said on Thursday that the UK decision would require doctors to reschedule consultations with tens of thousands of elderly and vulnerable patients to receive their second dose of the vaccine. The group called for change “Grossly unfair”.
Anthony Fauci, the leading infectious disease specialist in the United States, also gave his opinion on the UK decision in an interview on NBC’s Today Show on Thursday. Distributing the two doses is “Under consideration,” he said, although he did not specify by whom.
“I still think that if done correctly, you can take a single dose, reserve doses for the second dose and still get the job done,” said Fauci. But he added “you can make an argument, and some people do, about stretching doses and giving a single generalized dose and hoping that you get the second dose in time to give it to individuals.”
In its statement, Pfizer said that surveillance is necessary in any alternative vaccination scheme and that authorities must work to ensure that each recipient receives the maximum possible protection.
“Data from the Phase 3 study demonstrated that, while partial protection of the vaccine appears to begin 12 days after the first dose, two doses of the vaccine are needed to provide maximum protection against the disease, a 95% vaccine effectiveness,” He told Pfizer in his statement.
An FDA document with frequently asked questions about Pfizer and partners The BioNTech SE vaccine notes that the agency’s assessment of the vaccine’s safety and effectiveness was based on data from patients who received two injections three weeks apart.
(Adds FDA’s Peter Marks statement in the fourth and fifth paragraphs.)