Nurse Sandra Lindsay receives the second dose of a Pfizer coronavirus vaccine (COVID-19) at Long Island Jewish Medical Center on January 4, 2021 in Queens County, New York City.
Shannon Stapelton | Getty Images
BioNTech and its partner Pfizer warned Monday that they had no evidence that their jointly developed vaccine would continue to protect against Covid-19 if the booster shot is given later than has been tested in trials.
“Vaccine safety and efficacy have not been evaluated in different dosing schedules, as most trial participants received the second dose within the window specified in the study design,” the companies said in a joint statement, referring to a primary reinforcement program features given three weeks apart.
“There is no data to show that protection after the first dose is maintained after 21 days.”
Germany was considering on Monday whether it would delay the administration of the second dose to push scarce supplies further after a similar move by Britain last week. Separately, Denmark approved a delay of up to six weeks between the first and second vaccination.