FREDERIC J. BROWN / AFP via Getty Images
The U.S. Food and Drug Administration is expected to authorize the first updated versions of COVID-19 boosters this week since the start of the pandemic.
The new shots are reformulated versions of the Moderna and Pfizer-BioNTech vaccines. They are known as “bivalent” vaccines because they are designed to protect against the original strain and the highly contagious variant of omicron.
Specifically, the vaccines are designed to target omicron subvariants BA.4 and BA.5, which are the dominant strains that infect people and the most adept at sneaking into the immune system.
The hope is that the shots will bolster people’s declining immunity and provide stronger protection against catching the virus, its spread, and getting sick with COVID and the long-standing COVID.
The Biden administration plans to begin making new vaccines available after Labor Day to help dampen the impact of what could be yet another wave of infections this fall and winter.
“This is a very important moment in this pandemic,” Dr. Ashish Jha, the White House COVID-19 response coordinator, told NPR. “This is the first major vaccine update – the first major vaccine change – in the past two and a half years.”
But the formulation of the boosters and the process to authorize them sparked debate among scientists.
For the first time, the FDA is judging how well vaccines work without the results of tests done directly on people. To save time, the FDA is initially evaluating vaccines with tests on mice along with the results of tests performed on people of an older version of a bivalent vaccine.
Some experts worry that studies in mice aren’t very reliable in predicting how well vaccines work in people.
“It could be problematic if the public thinks the new bivalent boosters are a super strong shield against infections, and thus increase their behavioral risk and expose themselves to more viruses,” says John Moore, immunologist at Weill Cornell Medicine.
But federal officials defend the decision.
Studies in mice suggest that the new vaccines may be about 20 times more protective against omicron than the original vaccines and about five times more protective than the first attempt to create omicron-specific bivalent vaccines, Dr. Peter Marks, director of the Center for Biologics Evaluation and Research at the FDA, he told NPR in an interview.
“This makes us feel confident that they will do what they are meant to do, which is to produce a good immune response against the BA.4 / 5 variant, as well as refresh our overall response given the original vaccine component as well,” says Marco.
The decision to rely on mouse studies became necessary after the FDA in June rejected new boosters targeting the original omicron strain, known as BA.1, and instead asked vaccine companies to develop new vaccines targeting the strains that had replaced him.
Some scientists think there is a possibility that the new injections may also give people immunity that lasts longer than the original injections and perhaps even protect against new variants that emerge. But more research is needed to confirm this.
Some experts say the data from the BA.1 boosters indicate that any potential improvement could be rather modest at best.
“We want a silver bullet. And the decoy has become the silver bullet. And we’re putting all of our eggs in the vaccine basket,” says Dr. Celine Gounder, a senior researcher at the Kaiser Family Foundation. “I am very skeptical of how much improvement these vaccines will produce in terms of population immunity and prevention of serious diseases.”
Gounder also fears the country has given up on doing anything else to protect people, such as wearing masks and improving ventilation.
But others are more optimistic about the new boosters.
“Personally, I’m very excited about bivalent vaccines,” says Jenna Guthmiller, assistant professor of immunology at the University of Colorado.
“We really need an updated vaccine to provide protection against current omicron viruses and potentially any future omicron variants,” says Guthmiller. “I think it will be fine.”
After the FDA clears the vaccines, consultants from the Centers for Disease Control and Prevention will meet Thursday and Friday to decide whether to recommend them and who should receive them. CDC Director Rochelle Walensky will then have to sign that recommendation.
Some experts say only people who are at high risk due to their age or underlyingg health issues need to get another booster as the first few shots are still protecting most people from serious illness. Others say that anyone 12 and older who hasn’t recently been infected or boosted should get a new vaccination.
“I’d say anyone more than six months old from their previous thrust or previous infection should get a boost,” says E. John Wherry, an immunologist at the University of Pennsylvania.
“Any opportunity to get more population boosters to increase vaccine uptake will be a positive thing to help us overcome this pandemic,” says Wherry.
The Biden administration has purchased more than 170 million doses of the new boosters, which are expected to start becoming available after Labor Day.
It is unclear how much demand there will be for the new boosters, as many eligible people have not yet received the first or second booster.