US FDA okays for Covid booster targeting Omicron BA.4 & BA.5 variants

The US Food and Drug Administration (FDA) has recommended vaccine manufacturers to develop booster shots against Covid-19 targeting Omicron BA.4 and BA.5 variants.

While currently available vaccines have helped reduce hospitalisation and death caused by Covid, results from several observational studies have shown that effectiveness of primary vaccination wanes over time against certain variants, including Omicron.

The Omicron BA.4 and BA.5 variants, currently driving the fresh wave of Covid cases globally, are known to evade vaccine induced immunity.

The FDA recommendation is based on the advice of independent experts on the Vaccines and Related Biological Products Advisory Committee that voted in favour of including a SARS-CoV-2 Omicron component in Covid-19 vaccines that would be used for boosters in the US beginning in September.

"As we move into the fall and winter, it is critical that we have safe and effective vaccine boosters that can provide protection against circulating and emerging variants to prevent the most severe consequences of Covid-19," said Peter Marks, Director of the FDA's Center for Biologics Evaluation and Research, in a statement on Thursday.

"We have advised manufacturers seeking to update their Covid-19 vaccines that they should develop modified vaccines that add an Omicron BA.4/5 spike protein component to the current vaccine composition to create a two component (bivalent) booster vaccine, so that the modified vaccines can potentially be used starting in early to mid-fall 2022," he added.

The FDA, however, has not advised manufacturers to change the vaccine for primary vaccination, since it provides a base of protection against serious outcomes of Covid-19 caused by circulating strains of SARS-CoV-2.

Vaccine manufacturers like Pfizer, Moderna, and Novavax have already been testing Omicron-targeted versions of their shots.

Their early data, based on the BA.1 variant, promises a stronger immune response to the Omicron variant than existing shots.

The FDA advised the drugmakers to conduct additional clinical trials on BA.4 and BA.5 shots, as well as send in data from the BA.1 shots to the agency for evaluation.