In the United States, FDA said delaying the second dose for the Pfizer-BioNTech vaccine would be “premature and not rooted solidly in the available evidence.” The European Medicines Agency, which has also authorized the Pfizer-BioNTech vaccine for the European Union, basically agreed, but mixed its message by adding the booster could be as late as 42 days after the first shot, noting this occurred with some people in the Pfizer-BioNTech vaccine’s efficacy study. And a vaccine advisory group to the World Health Organization, which yesterday recommended that WHO put the Pfizer-BioNTech vaccine on its “emergency use” list, echoed FDA’s position.
Pfizer and BioNTech released their own statement objecting to changing the intended dosing schedule, which says to give the booster shot 3 weeks after the priming injection. “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,” the companies stated. “There is no data to demonstrate that protection after the first dose is sustained after 21 days.”