The Australian Health Protection Principal Committee (AHPPC) has reiterated the importance of booster vaccinations following its update to advice concerning reinfection resistance.
In a statement, the AHPPC indicated it now considers reinfection to be possible from 28 days after recovery from COVID-19. Previously, it was 12 weeks.
It comes amid several updates from Australian health authorities, who now recommend a fourth ‘winter dose’ of approved vaccine for adults over 50, and optional for those aged 30–49.
Why is it now 28 days?
The AHPPC updated its reinfection period from three months to 28 days following the emergence of new Omicron subvariants BA.4 and BA.5. These more contagious versions of the virus are better able to reinfect those who have had previous vaccinations or infections.
South Australia, the Northern Territory and Queensland are yet to issue an update to their guidelines, although the AHPPC is comprised of all state and territory chief health officers and is chaired by the Australian CMO.
How soon after reinfection can Australians get their winter booster?
Following its 7 July meeting, the Australian Technical Advisory Group on Immunisation (ATAGI) issued new advice on winter booster doses of approved COVID-19 vaccines, which has been approved by federal health minister Mark Butler.
All adults aged 50 are now recommended to receive a winter booster, in addition to the groups already advised to receive a fourth vaccine dose. Adults aged 30–49 are also eligible for a winter booster.
ATAGI also recommends that people should wait three months between either recovery from COVID-19 or their first booster before getting another jab.
It’s not yet clear whether the updated reinfection period advice from AHPPC will alter this advice, but ATAGI regularly reviews its recommendations in the light of most recent research.
What the chiefs say
NSW Chief Health Officer Dr Kerry Chant confirms that the Omicron BA.4 and BA.5 subvariants are circulating widely in NSW.
“They are more able to evade immunity gained from previous infection and vaccination reinfection is more likely and possible just weeks after a prior infection,” she says. “We’re urging people who have recently had COVID-19, even if they left isolation in the past four weeks, not to be complacent. If you develop symptoms again, make sure to test and isolate.”
ACT Chief Health Officer Kerryn Coleman points out that people who test positive outside of the 28-day period will now be treated as new cases, and they must report positive results to ACT Health.
“All Canberrans have a role to play in reducing the impact of COVID-19,” Coleman says. “Now is the time for all of us to act to protect ourselves, our loved ones, the health system, those who are more at risk and the broader community.”
WA Chief Health Officer Andy Robertson says that BA.4 and BA.5 are making up “an increasing percentage of our cases” – he says more than 60% of WA cases last week.
Victorian health minister Mary-Anne Thomas advocates sticking to the virus-management basics: “Wearing a mask, getting up to date with your vaccinations and ensuring indoor areas are well ventilated are small but effective steps Victorians and businesses can take to manage their own COVID-19 risk this winter.”
Matthew Agius is a science writer for Cosmos Magazine.
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