The period of time in which a COVID-positive person is considered immune after infection may be slashed from 12 weeks to 28 days following a recommendation by Australia's top public health officers.
The Australian Health Protection Principal Committee (AHPCC) last week said the rise of the BA.4 and BA.5 strains had also seen reinfections increase.
In a statement, the committee said the immune period should be adjusted as people were getting reinfected earlier.
"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," the statement read.
"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.
"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."
South Australia's Health Minister Chris Picton said the state would be looking at changing its rules around reinfection in the coming days.
"For 12 weeks people have had this 'get out of jail free card' for COVID," he said.
"Anecdotally, there have been people who have had reinfections who have been ringing various coronavirus hotlines saying, 'I think I'm infected' and people say 'oh well you can't be because of the 12 weeks', well actually you can."
SA Chief Public Health Officer Nicole Spurrier, who is part of AHPCC, said SA Health would begin counting reinfections in anyone testing positive after 28 days as early as today.
But she was unsure when changes around the immune period would impact close contact rules.
In South Australia, close contacts are encouraged to stay home, but can leave the house for work and school — although they are required to let their employer know they are close contact.
Close contacts must wear a mask when leaving the house and do five RATs over a seven-day period.
Currently, anyone who has tested positive to COVID is exempt from these rules for 12 weeks.
Booster shot time frames unchanged
From today, Australians over the age of 30 will now be eligible to get a fourth COVID booster shot.
Professor Spurrier said recommendations around booster shots were unchanged despite the immune period being reduced.
"ATAGI (Australian Technical Advisory Group on Immunisations) have been quite clear on this that it is a three-month period," Professor Spurrier said.
"It's three months between the first booster and the second or the winter booster dose and also three months from an infection."
She said ATAGI would continue to look at whether those time frames need to be adjusted.
