The Food and Drug Administration on Wednesday authorized new Covid-19 vaccines for emergency use for the first time since the original vaccines were approved in December 2020, with the Center for Disease Control approving it on Thursday. The new boosters from Pfizer/BioNTech and from Moderna are targeted at the BA.4 and BA.5 subvariants of the omicron variant. They’re also the engine of a new vaccine booster campaign in the United States as health officials brace for another surge in cases.
“As we head into fall and begin to spend more time indoors, we strongly encourage anyone who is eligible to consider receiving a booster dose with a bivalent COVID-19 vaccine to provide better protection against currently circulating variants,” said FDA Commissioner Robert M. Califf in a statement.
“Bivalent” refers to the fact that the vaccines contain genetic instructions for the immune system to target the original version of the SARS-CoV-2 virus that causes Covid-19, as well as the main variants in circulation now. The BA.4 and BA.5 subvariants are notorious for evading prior immunity to Covid-19, although older Covid-19 vaccines are still preventing hospitalizations and deaths from newer versions of the virus.
Before those shots can start going into arms, the Centers for Disease Control and Prevention has to weigh in and come up with guidelines for how to distribute these new shots. Advisers to the CDC are met and approved the boosters. They announced that the shots will be available to anyone above the age of 12. Meanwhile, the US government has already ordered 170 million doses.
As for who is eligible, the Moderna bivalent vaccine is available to anyone over the age of 18 as a first booster or a second booster, provided it’s been at least two months since the last shot. The Pfizer/BioNTech vaccine follows the same criteria except that it’s open to people ages 12 and up.
For both boosters, it does not matter which vaccine you had as your initial doses. However, the bivalent vaccines are only authorized as boosters, so at the moment, they don’t replace the original vaccines for people who are completely unvaccinated.
Officials didn’t specify whether the eligibility window is different for people who were recently infected with Covid-19, but researchers have found that surviving an infection can increase protection against reinfection. “A Covid infection in a vaccinated person — essentially, that functions as a booster,” Andrew Pekosz, a professor of microbiology and immunology at Johns Hopkins University, told Vox earlier this month. “So you probably don’t need to get a booster for anywhere from three to six months after your Covid infection.”
While the rate of Covid-19 deaths in the US has fallen sharply from its peak this past winter, deaths are still holding steady at roughly 400 per day. That’s because mask mandates and social distancing measures are all but gone, allowing more opportunities for the virus to spread. The latest variants are especially adept at jumping between people. The largest share of deaths comes from people with weaker immune systems, like older adults and those with certain preexisting health conditions, including some who are vaccinated. Shielding from vaccines also wanes over time, and with so many people months out from their last dose, millions could be susceptible to another infection.
Health officials hope that the new boosters formulated to target the latest variants will keep a lid on hospitalizations and deaths this fall. But boosters are only effective if people actually get them, and it’s clear not everyone is ready to roll up their sleeves. About one in five people in the US have not received any dose of a Covid-19 vaccine, and among those who are vaccinated, less than half are boosted. If the uptake of the bivalent vaccines is similarly low, they may not do much to stem the losses of another Covid-19 surge. And as long as the virus spreads, it mutates, increasing the chances of another dangerous variant emerging.
Some researchers have pointed out that the reformulated vaccines are only marginally better than the original versions of the shots, so they question whether it was worth holding out for them. Again, while the original versions of Covid-19 vaccines don’t hold off infections as well from the new variants, they still prevent most hospitalizations and deaths.
It’s also not clear yet whether vaccines will need to be revised on a regular basis. That hinges on changes to the virus itself and its public health impacts. Scientists are also studying universal Covid-19 vaccines that could potentially protect against future variants. Those vaccines are likely years away, but they could become the last shot most people would need.
Update, September 3, 2022, 10:50 am ET: This story was updated to include information on the CDC approving the boosters.