Two vaccines that specifically target the Omicron variant have been granted “provisional determination” by Australia’s drugs regulator, the first step in a process for getting the vaccines approved for use.

It comes as the BA.4 and BA.5 subvariants of Omicron drive a new wave of cases, prompting premiers to warn of increasing hospitalisations and deaths, and renewed calls to the public to wear masks in crowded indoor spaces.

While existing vaccines are very effective at preventing hospitalisation with and death from BA.4 and BA.5, they are less effective at stopping transmission and symptoms.

The surge in cases has put pressure on the Australian Technical Advisory Group on Immunisation (Atagi), which was meeting on Wednesday to consider whether fourth doses of existing vaccines should be recommended for the wider population as cases surge.

One of the challenges Atagi faces in making its decision is that for healthy people, three vaccine doses are very effective at preventing severe disease and death, and this combined with immunity from Covid-19 infections may mean approving a fourth dose for everyone is not effective.

The wider concern may be ensuring booster doses are accessible for the most vulnerable, with elderly and under-vaccinated people with comorbidities overrepresented in Covid deaths.

Atagi will also be considering whether it is worth waiting for better, more targeted boosters on the horizon, such as Pfizer’s.

However, the two Pfizer vaccines granted provisional determination on Wednesday target the spike protein of the Omicron BA.1 variant of concern. Data is still being collected by Pfizer on how effective the vaccines might be against the BA.4 and BA.5 Omicron subvariants becoming dominant in Australia.

Prof Ugur Sahin, the chief executive of BioNTech which developed the vaccine in conjunction with Pfizer, said: “Omicron has newly evolving sublineages that have outcompeted BA.1 and exhibit a trend of increasing potential for immune escape.

“We will therefore remain vigilant and are prepared to rapidly adapt our Omicron-adapted vaccine candidates to emerging sublineages if epidemiological and laboratory data suggest.”

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Provisional determination is an early step in the vaccine approval process. To grant provisional determination, the Therapeutic Goods Administration would have required preliminary clinical data and evidence from Pfizer of a plan to submit more comprehensive clinical data down the track. It also would have needed to see a strong argument for why the vaccines are needed.

Now that the TGA has granted provisional determination, Pfizer can apply for “provisional registration” of the vaccine. Pfizer has six months to do this, and will need to submit further data to the TGA from human trials about how the treatment works and its safety.

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Once the TGA has scrutinised the data, and if it is satisfied with it, it may grant Pfizer “provisional approval” for the vaccines to be used in Australia. Further data must be collected and given to the TGA even if this occurs, and the government will also await recommendations from Atagi.

In a statement, the TGA said it would “undertake a rigorous assessment of the safety, efficacy and quality of these vaccines with the highest priority”.

Source: The Guardian