The first Australian research into the Omicron variant of COVID-19 has confirmed the importance for boosters that could reduce serious infection and hospitalisation by up to 98 per cent, researchers say.
It comes as the Australia's peak expert panel on vaccines, ATAGI, is expected to update its booster advice to government next week incorporating the latest research findings from laboratories around the world.
The Australian findings also found most currently used treatments did not work well at fighting against the new COVID variant of concern in the tests conducted in an ultrasecure laboratory at the Kirby Institute at UNSW.
Australia has good supplies of the one treatment, Sotrovimab, that was found to be effective, and double-dose vaccination rates are high, reaching 98.3 per cent in the ACT.
Anthony Kelleher, director of the Kirby Institute, said that people with higher levels of neutralising antibodies that come from booster vaccinations were less likely to acquire the infection and less likely to progress to serious symptoms.
"This is still very early days in our understanding of Omicron ... we need to be careful about making all efforts to reduce the rate of transmission and that includes people taking up the offer that has been made of booster vaccinations," Professor Kelleher said.
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Compared with the vaccine protection offered against the original and earlier variants, the two-doses most Australians have received offer very limited protection against symptomatic infection from Omicron, so the researchers looked ahead to what impact boosters could have.
The researchers, led by Stuart Turville, an associate professor in immunovirology and pathogenesis at the institute, looked at patients that had recovered from infection with a good response and then had two doses of vaccine, mimicking the three levels of immune stimulation that would come with a booster shot.
The immune protection in those patients with the equivalent of a booster shot averaged about 22-fold lower against Omicron, but still more than no protection and the researchers emphasised that even some protection helps in reducing severe symptoms and hospitalisation.
"We saw zero protection with the antibodies from double vaccinated [subjects]," Dr Turville said referring to those without the equivalent of a third shot.
"And it was irrespective of the type of vaccine. We don't need to talk about AstraZeneca or Pfizer, both of them are zero."
The data also could help determine the ideal time for boosters to be given.
The researchers said the high immune response from a booster shot wanes after six months, indicating there probably will be the need for another booster in six months.
Dr Deborah Cromer said it was unknown what variant will emerge in another six months' time, so it was important to focus on what data was known now.
"Having a booster shot with an mRNA vaccine massively increases neutralising antibodies and then results in protection against any disease of really quite high levels, up to around 85 to 86 per cent against symptomatic disease and around 98 per cent protection against severe disease," she said.