TGA approves Moderna's Omicron-containing booster dose

The Therapeutic Goods Administration (TGA) has provisionally approved Moderna’s bivalent COVID-19 vaccine, mRNA-1273.214 (Spikevax Bivalent Original/Omicron), for use as a booster dose in adults 18 years and over. This is the first bivalent COVID-19 vaccine approved for use in Australia, triggering an immune response against two different COVID-19 variants: the original virus and the BA.1 Omicron variant.

Spikevax Bivalent Original/Omicron is a next-generation bivalent vaccine that contains 25 µg of mRNA-1273 (Spikevax) and 25 µg of a vaccine candidate targeting the Omicron variant of concern (BA.1). The vaccine should be administered at least three months after a primary series and/or previous booster dose with SPIKEVAX or other authorised COVID-19 vaccine, in accordance with official recommendations.

The decision from the TGA is based on clinical trial data from a phase 2/3 trial, in which mRNA-1273.214 met all primary endpoints, including superior neutralising antibody response against Omicron (BA.1) when compared to a 50 µg booster dose of mRNA-1273 in previously uninfected participants. A booster dose of mRNA-1273.214 increased neutralising geometric mean titres (GMT) against Omicron approximately eightfold above baseline levels.

In addition, mRNA-1273.214 elicited potent neutralising antibody responses against the Omicron subvariants BA.4 and BA.5 compared to the currently authorised booster (mRNA-1273) regardless of prior infection status or age. mRNA-1273.214’s reactogenicity and safety profile is meanwhile consistent with the currently authorised Spikevax (mRNA-1273) booster.

Moderna has already received approval for mRNA-1273.214 in the UK and Switzerland and has completed regulatory submissions for the next-generation vaccine worldwide. The potential use of this vaccine in Australia’s COVID-19 vaccination program is still to be determined, with the Australian Technical Advisory Group on Immunisation (ATAGI) set to provide advice to the federal government on these matters in the coming weeks.

The news comes around one week after ATAGI gave the green light for Novavax’s COVID-19 vaccine to be used in adolescents aged 12–17 years for their primary course of COVID-19 vaccination, or three doses for those who are severely immunocompromised. The product is a spike protein-based vaccine, with each 0.5 mL dose containing 5 µg of SARS-CoV-2 spike protein and 50 µg of Matrix-M as an adjuvant.

The recommended primary course dosing schedule for Novavax COVID-19 vaccine is two doses around eight weeks apart, while the manufacturer’s dosing schedule is two doses at least three weeks apart. The extended interval of eight weeks is consistent with other COVID-19 vaccines and evidence from other COVID-19 vaccines has suggested a longer dose interval may improve vaccine effectiveness, though such evidence does not currently exist in respect to Novavax; the longer dose interval may also reduce the risk of myocarditis and pericarditis, particularly for those most at risk of these side effects (males aged 12–39 years).

Australian adolescents will be able to book in to receive Novavax from 5 September. Novavax is not currently registered by the TGA for use as a booster dose in this age group; however, ATAGI have advised that Novavax can be used as a booster in instances where no other COVID-19 vaccine brand is suitable.

Image credit: iStock.com/Lacheev

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