Many coronavirus vaccines are facing setbacks, from low rates of efficacy to concerns over blood clots.
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,” Kessler said.
Initial data has shown that vaccines from Moderna and partners Pfizer and BioNTech retain most of their effectiveness for at least six months.
Even if that protection lasts far longer, experts have said that rapidly spreading variants of the coronavirus and others that may emerge could lead to the need for regular booster jabs – such as with annual flu jabs.
The US is also tracking infections in people who have been fully vaccinated, Rochelle Walensky, director of the 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.
US officials made statements on booster jab preparations as top UN officials urged rich countries to donate excess COVID-19 vaccine doses to the COVAX programme supplying lower-income countries in a bid to end the pandemic and get the global economy back on track.
The US, which this year donated half of a pledged $4bn to COVAX, has yet to make new commitments.
“As we’re getting to that point where we’re confident that every American can be vaccinated, we will be leaning into doing more around the world,” Secretary of State Antony Blinken told NBC’s Meet The Press on Sunday.
Blinken noted that Congress had recently provided more than $11bn for America’s global COVID-19 response.
The US has seen over 31 million confirmed coronavirus cases and nearly 3 million deaths since the pandemic began, according to the Johns Hopkins University tally.