Moderna deal closes crucial gap in Australia’s vaccine strategy

The deal the federal government has struck with Moderna addresses a major gap in Australia’s vaccine strategy.

While the Pfizer vaccine that will be given to those under 50 shows efficacy against variants including the UK variant and the South African variant, both of which have arrived in Australia, an initial study has shown that while the AstraZeneca vaccine is effective against the UK strain, it is virtually ineffective against the SA strain.

While the original Wuhan strain of COVID-19 is likely to remain the dominant virus in Australia as cases inevitably emerge after borders open, variant strains have proven more contagious and have become dominant in the countries where they are circulating widely.

That’s why boosters are so important, and Moderna is one of the most advanced companies in developing boosters. They’re way ahead of AstraZeneca, because Moderna’s is an mRNA vaccine, and mRNA vaccines are able to be adapted much more quickly to combat variants than viral vector vaccines such as AstraZeneca’s.

Australia’s agreement to purchase 25 million doses of Moderna vaccine is in two parts. We are getting 10 million of their original vaccine formulated against the Wuhan strain in the latter part of this year, and next year we’ll get 15 million doses of the booster the US biotech has been developing.

Moderna hasn’t focused on the UK strain in developing its booster, since its original vaccine has good efficacy against the UK strain. It’s developing two booster shots that are both being formulated against two new strains: SA strain and the Brazil strain. One booster, known as mRNA-1273.351, is formulated specifically with the SA variant in mind, and the other is a multivariant booster shot that is a 50/50 mix of its original vaccine and the new mRNA-1273.351 booster. Both boosters are designed to be given as a single shot rather than a two-dose regimen.

The Moderna headquarters in Cambridge, Massachusetts. Picture: AFP.

On May 6th, Moderna released data from its initial studies into these two boosters. The data showed that the measure of antibodies in the blood to the Wuhan strain remained high in 37 out of 40 participants in the US study who had all been given the original Moderna shot. But antibodies were undetectable against the SA and the Brazil strains. Two weeks after receiving the variant-specific booster mRNA-1273.351, antibodies against these two strains had increased to levels that were similar or higher to the peak antibody levels recorded against the Wuhan strain following the original vaccination.

Although it is yet to approve the original Moderna vaccine, the Therapeutic Goods Administration will not require data from additional large-scale clinical trials in order to approve the booster shot. That means it will be demonstrate in the real-world how effective the booster shot proves to be.

Currently, vaccinated Australians will be well protected against the original and the UK strains whether they get AstraZeneca or Pfizer. But if the SA strain does emerge again in Australia and circulate, the Moderna booster shot could prove to be very important.