The US Food and Drug Administration (FDA) has authorized new mRNA vaccine booster shots targeting the BA.4 and BA.5 Omicron variant of SARS-CoV-2. The authorization marks the first updated COVID-19 vaccines to be made available in the United States since the original vaccines became available in late 2020.
“The COVID-19 vaccines, including boosters, continue to save countless lives and prevent the most serious outcomes (hospitalization and death) of COVID-19,” explained FDA Commissioner Robert Califf. “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.”
The FDA authorization follows a contentious few months of experts disagreeing over the best path to take for COVID vaccine boosters. Back in early July the FDA diverged from many other regulatory agencies around the world by advising vaccine manufacturers it would require a COVID vaccine booster targeting the BA.4/5 subtype of Omicron.
Since the beginning of the year both Pfizer and Moderna have been working on updated Omicron mRNA boosters aimed at the BA.1 subtype. By June that development progressed into human trials, with preliminary data indicating the booster was more effective compared to the original formulation.
An advisory group to the World Health Organization (WHO) in June recommended this BA.1 formulation for 2022 booster programs, despite other Omicron lineages already spreading. The group indicated it was better to focus booster programs on a well-tested BA.1 formulation than to try and chase the current Omicron subtype.
The United Kingdom, European Union, and Australia have all followed on with the BA.1 booster plan but the FDA pushed on with a newer formulation. Pfizer and Moderna quickly responded, and now have initial supplies of the BA.4/5 booster available for US distribution.
“In less than three months, we were able to develop and manufacture an Omicron BA.4/BA.5-adapted vaccine,” said Ugur Sahin, co-founder of BioNTech, the mRNA company working with Pfizer on the vaccine. “This milestone further underlines the strength of rapidly adaptable mRNA vaccines against the this continuously evolving virus.”
While most experts agree there is unlikely to be any significantly different safety concerns between the original mRNA formulation and BA.1 or BA.4/5 boosters, what is unclear is whether this BA.4/5 booster will be more effective than the BA.1 shot. Due to the pace of its development the FDA only has a small volume of animal data to show the BA.4/5 booster triggers a strong immune response, as opposed to the BA.1 booster, which has been studied in humans.
Celine Gounder, from NYU Langone Health, is unsure this new booster will be that much better than the original vaccine.
“There’s no reason to think they’ll be unsafe,” Gounder said to NBC News. “But whether they’ll provide significantly more protection than the original vaccines? Of that I’m skeptical.”
The FDA’s new booster authorization allows all adults over the age of 18 access to the Moderna booster and all those over the age of 12 access to the Pfizer booster. The recommendation for the booster is for it to be taken no earlier that two months after any prior COVID vaccine dose. However, the exact dosing advice will be established by an advisory group to the Centers for Disease Control and Prevention (CDC) in the coming days.
Both Pfizer and Moderna indicate supplies of the new vaccine are ready to be distributed. Pfizer in particular has said it has 15 million doses that can be shipped immediately, so the vaccine could begin its roll-out as soon as next week.