Australians over 30 will be eligible to receive a fourth dose of approved COVID-19 vaccines from Monday, following new recommendations from the Australian Technical Advisory Group on Immunisation (ATAGI).
The new advice accepted by Australian health minister Mark Butler means adults over 50 years are now recommended to receive a winter booster. It has also expanded fourth-dose eligibility to those aged 30–49, although notes that benefit for this group is “less certain.”
That’s because current data suggests younger age groups are less likely to develop severe disease relative to those over 50.
The decision comes amid slow take-up of third-dose boosters and in anticipation of a case surge from Omicron’s BA.4 and BA.5 subvariants in Australia. Almost six million eligible people are yet to receive their third dose (the first booster).
Until now, only those over 65 were eligible to receive the winter booster – just 60% of this group have had this fourth dose. Expanding eligibility is anticipated to ease healthcare system pressures as cases increase.
“These clever variants have learned to evade our immune responses and even ignore vaccine induced antibodies,” says Murdoch University professor in viral immunology Cassandra Berry. “So booster shots will help lift our levels of protection so we can manage disease, reduce hospitalisations and hopefully prevent more deaths.”
Boosters improve antibody levels
While new Omicron subvariants are responsible for the increase in cases, the first Omicron-specific vaccines are still in development. Until these next-generation jabs arrive, experts say current boosters are still effective at bumping-up immunity against Omicron variants.
That can lessen the risk of severe illness.
“We do know that vaccine-induced antibodies are less efficient in binding the Omicron variant,” explains Associate Professor Menno van Zelm, Head of the Laboratory for Allergy and Clinical Immunology and Deputy Head of the Department of Immunology and Pathology at Monash University.
“However, it is clear from scientific data that booster vaccinations do improve both the total antibody levels and the capacity of these antibodies to bind Omicron.
“This will undoubtedly ensure that after a booster dose, your risk of severe disease is strongly reduced, thus protecting yourself, and people around you, either directly, or indirectly by alleviating pressure on the healthcare system.”
Fourth dose expansion begins on Monday; AHPPC changes reinfection period
Newly eligible people will be able to receive a fourth dose of the vaccine from Monday 11 July.
As of last Thursday, ATAGI was recommending the winter booster following a three-month interval between the more recent of infection or a first dose. That means those currently infected with COVID would wait until October for their booster jab.
But on Friday, the Australian Health Protection Principal Committee (AHPPC) released a statement that may alter the timing part of this recommendation.
“Given reinfections may occur as early as 28 days after recovery from a previous COVID-19 infection, the AHPPC advises that the reinfection period be reduced from 12 weeks to 28 days,” read the statement. “People who test positive to COVID-19 more than 28 days after ending isolation due to previous infection should be reported and managed as new cases.”
A further announcement clarifying the recommended interval between infection or a first dose and the winter booster seems likely.
The AHPPC statement emphasised the new wave of COVID infections driven by the BA.4 and BA.5 Omicron subvariants. “We expect that this wave will lead to a substantial increase in infections, hospitalisations and sadly, deaths, at a time when our communities and health systems are already under strain,” reads the statement. “Without increased community and public health actions, this impact may be similar to that experienced during the BA.1 wave in January this year.
“BA.4 and BA.5 are associated with increased immune escape and we are likely to see rates of reinfection rise among those who have previously been infected with an earlier COVID-19 variant and those who are up to date with their vaccinations. Vaccination continues to be the most important protection against severe illness.”
Thousands of new cases are now being reported each day – nationally there were nearly 42,000 in the 24 hours before the 8 July statistics update – and Australian health minister Mark Butler is hoping to see the expanded winter dose eligibility improve the nation’s coverage against the new variants.
“There was a terrific take up of the first two doses of vaccine in Australia,” Butler says. “We have one of the highest rates of double-dose vaccination in the world, but what we know about the Omicron variants is that two doses of vaccine is simply not enough to give you protection. Even if you have been infected.
“Hospitalisation numbers now are about 3800 […] That is still a fair way below the peak we saw in January, which was over 5000. But there’s no question those numbers are going to continue to increase.”
There are currently almost 290,000 active COVID cases in Australia, with 3,899 hospitalisations.
Matthew Agius is a science writer for Cosmos Magazine.
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