It is a "likely scenario" that coronavirus vaccines will require additional annual booster shots, Pfizer CEO Dr. Albert Bourla said in an interview with CVS Health on Thursday.
"The duration of the immunity was unknown. Until yesterday, there was data only about the first 90 days," Bourla said, adding that the data published on Wednesday showed the Pfizer vaccine still provided people with "extremely, extremely high protection" from being infected with COVID-19.
He said that while this is "very, very good news," he also added that "vaccine protection goes down over time," adding that the virus is more similar in build and rates of mutation to the influenza virus than the polio virus.
"I think there will be a need, based on this data, for re-vaccinations. We need to see for how often we will need to do that, that remains to be seen."
"A likely scenario is that there will likely be a need for a third dose somewhere between six and 12 months [after the initial vaccination] and from there, there will be an annual revaccination."
"But all of that needs to be confirmed," he said, adding that "the variants will play a key role."Meanwhile, the United States is preparing for the possibility that a booster shot will be needed between nine to 12 months after people are initially vaccinated against COVID-19, a White House official said on Thursday.
While the duration of immunity after vaccination is being studied, booster vaccines could be needed, David Kessler, chief science officer for President Joe Biden's COVID-19 response task force told a congressional committee meeting.
"The current thinking is those who are more vulnerable will have to go first," he said.
Initial data has shown that vaccines from Moderna Inc and partners Pfizer Inc and BioNTech SE retain most of their effectiveness for at least six months, though for how much longer has not been determined.
Even if that protection lasts far longer than six months, experts have said that rapidly spreading variants of the coronavirus and others that may emerge could lead to the need for regular booster shots similar to annual flu shots.
Data published jointly last month by Israel's Health Ministry, along with Pfizer, showed that the Pfizer coronavirus vaccine is about 97% effective against severe cases and 94% against asymptomatic infections, new data jointly released Thursday by the pharmaceutical company and the Health Ministry shows.
The United States is also tracking infections in people who have been fully vaccinated, Rochelle Walensky, director of the US Centers of Disease Control and Prevention told the House subcommittee hearing.
Of 77 million people vaccinated in the United States, there have been 5,800 such breakthrough infections, Walensky said, including 396 people who required hospitalization and 74 who died.
Walensky said some of these infections have occurred because the vaccinated person did not mount a strong immune response. But the concern is that in some cases, they are occurring in people infected by more contagious virus variants.
Earlier this month, Pfizer and partner BioNTech said their vaccine was around 91% effective in preventing COVID-19, citing updated trial data that included more than 12,000 people fully inoculated for at least six months.