The agency issued the emergency use authorization for the booster Wednesday, making it the third available to people 12 and older – joining the Pfizer-BioNTech and Moderna shots.
It is available to those who are at least six months removed from receiving the two-dose primary series of any of the three jabs.
The Novavax booster shot was designed to fight the ‘wild type’ strain of the coronavirus that first emerged in late 2019 and early 2020.
In August regulators approved bivalent boosters from Pfizer and Moderna targeting the BA.5 and BA.4 strains of Omicron, which now make up about 68 per cent and 0.6 per cent of cases respectively.
The Omicron variant has proven capable of evading some of the protection conferred through vaccinations, though the shots remain effective against severe illness requiring hospitalization and death.
Uptake for the newly approved bivalent boosters was minimal, with Americans deciding not to get them despite appeals from the Biden Administration.
Novavax said its booster triggered a robust antibody response against Omicron subvariants BA.1, BA.2 and the dominant BA.5 subvariant in adults who received the primary series of shots eight to 11 months prior.
The move by American officials comes as European officials approve shots for children as young as six months – matching the US for the initial batch of shots.
Still, Novavax has not yet presented real-world efficacy data on how its shots perform against the BA.5 subvariant.
‘We have ongoing trials further exploring the Novavax COVID-19 vaccine’s potential as an effective booster against these variants, including BA.4/5, and look forward to sharing these data,’ said Dr Gregory Glenn, President of Research and Development at Novavax.
Moderna and Pfizer-BioNTech also have not provided real-world data pointing to the bivalent shot’s efficacy in targeting the omicron offshoots.
The Novavax shot offers vaccine holdouts an alternative to the mRNA technology that supports the Pfizer-BioNTech and Moderna vaccines.
The Novavax vaccine relies on protein-based technology similar to what is used to create the flu, hepatitis B, and shingles vaccines.
Lab-engineered spike proteins mimic the one on the coronavirus pathogen that binds to cells and infects people.
The engineered spike protein is coupled with an adjuvant – in this case derived from a tree native to South America – which turbocharges the immune response to the real thing.
Novavax aims to reach the population who have yet to be boosted with an mRNA vaccine.
Many people abstained from the mRNA shots due to distrust of the technology and/or anxiety about the safety of a vaccine developed at such an accelerated pace.