US FDA authorises second Omicron-updated Covid booster for older adults

The US Food and Drug Administration on Tuesday authorised a second dose of Omicron-targeting Covid-19 vaccines for older adults as well as those with a weak immune system.

The agency also said the updated shots from Pfizer-BioNTech and Moderna would become the new primary Covid-19 vaccine, and withdrew its emergency-use authorisation for the older messenger RNA vaccines that target only the original version of coronavirus.

People aged 65 years and older can now receive a second dose of the updated "bivalent" booster four months after the first, while immunocompromised people can get an additional shot of the updated vaccine after two months, the agency said.

"We're hoping that it's going to encourage people who have not received the bivalent booster to go out and consider getting one," Dr Peter Marks, director of the FDA's Center for Biologics Evaluation and Research, said at a news conference.

Most Americans over the age of 65 had not yet received a bivalent booster, he said.

The FDA decision comes a day before the US Centers for Disease Control and Prevention's (CDC) panel of expert advisers meets to discuss updating US Covid-19 vaccination guidelines.

The group is not expected to vote on their use, but the CDC director needs to sign off on the second Omicron-tailored shots from Pfizer-BioNTech and Moderna for them to become widely available.

In February, a working group of expert advisers said there was not enough evidence to support recommending more than one Covid-19 booster shot a year.

Marks said he believes the data currently supports a six-month interval for people over 65. Immunocompromised people might need more individualized recommendations because their various conditions could influence how often they need to receive booster shots, he said.

The FDA authorised the retooled Covid-19 boosters in August that target the BA.4 and BA.5 Omicron subvariants, along with the original strain of the coronavirus. Since then, the vast majority of the Covid-19 shots, more than 85 percent, that have been given in the US have been bivalent shots, according to CDC data.

Still, only around 17 percent of the US population have gotten the updated boosters. Among people aged 65 years and older, the uptake is higher, with nearly 43 percent receiving the newer shot.

The authorisation withdrawal of the original Covid-19 vaccines comes as the FDA plans to shift to an annual Covid-19 booster campaign with an updated strain, similar to the way Americans get their flu shots.

"We'll look to do our best to select what we believe to be likely to circulate the following fall-winter season, and use that in the vaccine composition," Marks said.

The FDA said it will hold a meeting of its advisers in June to discuss that strain composition, with vaccine manufacturers expected to update their shots once they are selected.

Novavax Inc, which missed out on the pandemic vaccine windfall enjoyed by rivals Pfizer and Moderna, is also preparing to update its vaccine for the fall, even though its protein-based shots may take longer to manufacture than mRNA counterparts.

The FDA's announcement on Tuesday does not impact the availability of the company's shots, Novavax said.

The company said it is manufacturing several vaccine options before getting regulatory clearance and continues to collaborate with the FDA to develop an updated vaccine for the fall campaign.

Marks said the FDA was "working with all the different companies to try to make sure that we have the appropriate vaccines available, timely, for the fall".

- Reuters