‘No time to wait’: Virus experts push for fourth COVID booster shots

Australia should approve a fourth COVID-19 booster shot for the entire adult population within months if the wait for vaccines that target new Omicron variants drags on, epidemiologists say.

Federal Health Minister Mark Butler said a third wave of Omicron infections was on the way, after announcing a major review of COVID-19 vaccine purchases on Friday morning.

Australia’s Therapeutic Goods Administration is considering an application from vaccine manufacturer Moderna for a new COVID-19 booster shot that targets the Omicron variant B4.1, as well as the original Wuhan strain of the virus.

But epidemiologists and immunologists caution against waiting too long for a premium vaccine, saying that a fourth booster shot of the current vaccine could be more effective if rolled out sooner.

This week the US Food and Drug Administration (FDA) voted to allow an Omicron-specific vaccine to be rolled out from September this year, and went a step further, advising manufacturers to update their vaccines to target both the BA.4 and BA.5 Omicron sub-variants. The precise formula has not been tested in people yet.

Pfizer and Moderna have developed their shots to target the original version of the variant, BA.1, and will need to redesign their vaccines to target the later strains.

Australia’s vaccine advisory panel is considering delaying a recommendation that more people get a fourth COVID booster shot, until a better Omicron-targeting vaccine is available. Professor Allen Cheng, who is a voting member and the former chair of the Australian Technical Advisory Group on Immunisation, said the expert group was watching the United States closely.

“The alternatives are that maybe there will be a better variant vaccine and if we just wait a few months longer we will have access to that in Australia,” Cheng said last week.

But Jamie Triccas, a senior immunology professor at Sydney University, said waiting for data about the efficacy of vaccines targeting new Omicron sub-variants could be problematic.

“I would think if it looks like there’s going to be a delay in approving those new variant boosters, or if there’s going to be issues with access – so how much can they produce in a short period of time – I would think that we’d have to look closely at maybe scheduling a fourth dose just to keep the level of protection community,” Triccas said.

“If for most people it’s been six months since the last dose and high levels of Omicron are circulating and the emergence of BA.4 and BA.5 is ticking up as well, I would say [the need for a fourth dose] should be a conversation we should seriously be having now.”

Vaccine researcher Professor James Triccas in a lab at Sydney University.Credit:Nick Moir

Epidemiologist Nancy Baxter, head of Melbourne University’s School of Population and Global Health, said an Omicron-specific booster would be highly beneficial. But it would be detrimental to wait any longer than three months for it, she said.

“The problem would be if we are planning in six months to have a normal Omicron booster … in six months, who knows what’s going to happen? But if we’re planning in the next three months to have an Omicron booster, that makes a lot of sense.

“This is going to be a winter without respite. So if they do have an effective Omicron-specific vaccine, it might make sense to roll it out in three months.”

Baxter said it was likely we would be in an “Omicron phase” for a while, but pointed out that committing to a booster shot that targets specific COVID-19 variant strains posed challenges when the virus was continually mutating.

Head of Monash University’s epidemiological modelling unit James Trauer said Australia’s high death rate from COVID-19 meant there should be no delay in approving fourth booster shots. He said improving the rate of third and fourth vaccinations should be a matter of priority. More than 300 Australians are losing their lives to COVID-19 each week.

“We’ve got fairly high death rates, they are a higher than a lot of countries in western Europe at the moment,” Trauer said. “I think people have lost quite a bit of protection from when they were vaccinated.”

Associate Professor James Trauer.

A Department of Health and Aged Care spokesman said Moderna had submitted an application for provisional registration for a bivalent COVID-19 vaccine that would target the original, ancestral strain and the Omicron BA.1 strain.

“As the evaluation progresses, the TGA will continue to seek information from Moderna Australia, until all required information is provided and a regulatory decision can be made.”

Butler said Australia was “not performing well” on the third and fourth dose takeup. Almost 6 million Australians who are eligible for a third dose have not yet had it. Sixty-four per cent of eligible aged care residents have received their fourth dose.

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