Pfizer chief sees need for COVID-19 booster shot within a year

Pfizer Chief Executive Albert Bourla said people will "likely" need a booster dose within 12 months of getting vaccinated, with need for annual shots.

"There are vaccines like polio where one dose is enough. And there are vaccines like flu that you need every year. The Covid virus looks more like the influenza virus than the polio virus," highlighted Bourla.

His observations, which were broadcast during an event held in April, was made public on Thursday.

Initial data has shown that vaccines from Moderna and partners Pfizer and BioNTech 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.

A White House official echoed the same sentiments on Thursday, highlighting that the country is preparing for the possibility that a booster shot will be needed between nine to 12 months after people are initially vaccinated.

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.

The country is also tracking infections in people who have been fully vaccinated, Rochelle Walensky, director of the U.S. Centers of Disease Control and Prevention told the House subcommittee hearing.

Of 77 million people vaccinated in the US, there have been 5,800 such breakthrough infections, Walensky said, including 396 people who required hospitalisation 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 per cent effective in preventing COVID-19, citing updated trial data that included more than 12,000 people fully inoculated for at least six months.