Well-Being Prevention & Cures

Reinfection period from COVID-19 may be as short as 28 days: Australia’s health officials

Reinfections that are detected 28 days after a previous isolation period should be treated as new infections and cases, they say.

Story at a glance


  • Health officials in Australia recommend shortening the reinfection period from 12 weeks to 28 days.

  • Australia is experiencing a wave of BA.4 and BA.5 omicron cases.

  • These subvariants are expected to lead to a rise in cases in the U.S. and potentially another wave. 

Health experts have growing concerns regarding reinfections of the SARS-CoV-2 coronavirus, especially as more data suggest that immunity from previous infection is not as protective against the newest omicron variants. Australia’s health officials have recommended that the immune period post-infection be shortened, which would affect how often people would need to test and quarantine if exposed to a COVID case.  

According to a report from July 8, the Australian Health Protection Principal Committee acknowledge that reinfections can occur as early as within 28 days and 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,” the report stated. 

Australia is in the Southern Hemisphere and is experiencing winter now. There was a BA.1 omicron wave in January, and there is currently a wave driven by the BA.4 and BA.5 omicron subvariants. These two subvariants “are more able to evade immunity gained from previous infection and vaccination reinfection is more likely and possible just weeks after a prior infection,” said New South Wales Chief Health Officer Kerry Chant to Cosmos Magazine. “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.”  

So far, five states in Australia have updated their official health advice to reflect the shorter reinfection period. All adults over the age of 50 are also advised to get their winter booster shots. 

In the U.S., the Centers for Disease Control and Prevention’s advice says that reinfections can occur within 90 days of a first infection. U.S. government officials are warning that the BA.5 omicron variant may lead to a wave of new cases. Positivity rate, cases and hospitalizations are trending up after plateauing for a few months following the original omicron wave. Community level transmission is high or medium in many parts of the country, although many people in cities around the country like New York seem to be ambivalent about it. 

The World Health Organization’s Director-General Tedros Adhanom Ghebreyesus warns that this combined with the fact that surveillance is lacking could be a problem, saying in a statement on July 12 that “surveillance has reduced significantly – including testing and sequencing – making it increasingly difficult to assess the impact of variants on transmission, disease characteristics, and the effectiveness of counter-measures.” 

Many health experts are prioritizing looking at testing positivity rate as a more accurate indicator of COVID trends, rather than number of cases. In New York, the positivity rate has risen rapidly in the last few weeks and currently is at 15 percent for the seven-day average. This rate is as high as it was in January in the middle of the first omicron wave. 

“New waves of the virus demonstrate again that the COVID-19 is nowhere near over. We have safe and effective tools that prevent infections, hospitalizations and deaths. However, we should not take them for granted,” Tedros said.