A growing number of Australians are catching COVID-19 for a second time as the country grapples with another surge in infections, but a lack of official data makes it hard to pinpoint exactly who is getting it twice.
Raelene Roede is a 50-year-old kindergarten teacher from Geelong, south-west of Melbourne, who caught COVID-19 for the first time after New Year's Eve in January.
After an extended bout of isolation – made longer due to January's infamous testing delays – and a week spent feeling pretty sick, Ms Roede made a full recovery and returned to her daily gym routine.
In mid March, after a trip to a local nightclub and her daughter testing positive, Ms Roede also returned a positive rapid antigen test – just over two months after recovering from her initial infection.
"I was not expecting the second time," she said.
She is not alone.
UNSW senior lecturer and respiratory epidemiologist Nusrat Homaira said data was showing that with the Omicron variant, reinfections were becoming more common.
"With Omicron, we see that people are 10 times more likely to get reinfected compared to the Alpha, Beta or Delta variant," Dr Homaira said.
And while getting sick and having to isolate again will cause a burden on the community and the economy, the good news is early data is showing reinfections are likely to be less severe.
Overseas studies show growing number of Omicron reinfections
As more individual stories of reinfection emerge, it is difficult to know exactly how common it is in Australia, because there is no publicly available data on it yet.
Epidemiologist and associate research fellow at the Burnet Institute, Mike Toole, said studies in the United Kingdom had found only about 1 per cent of new cases were reinfections in November 2021.
He said in March with Omicron, the reinfection rate in the UK increased to about 14 per cent.
Professor Toole said other overseas studies were also backing reports that reinfections were increasing.
"Qatar did a big survey, and found that during those original strain — Alpha, Beta, Delta, if you got infected, you were about 90 per cent protected from other infection," he said.
"Now it's down to just over 50 per cent."
No Australian data available yet on reinfections
When asked about reinfection rates, federal health authorities deferred to the states.
Most states or territories are not publicly reporting this data yet – with some admitting they are not even tracking it.
Queensland Health said it did not have the figures, while WA health authorities said they were recording reinfections but there had not been many there yet.
The Northern Territory was the only jurisdiction to provide a number, with 13 known reinfections in the Territory, from the nearly 52,000 cases it has recorded during the pandemic.
Victorian authorities said it did have some reinfection data but it was still working on making it publicly available.
Health experts have warned if people who have already had the disease do not realise they are still at risk they may also be less likely to test, especially if their second infection was less severe.
That was the case for Ms Roede, though she still got tested straight after her daughter's positive result.
"I knew the first time [I was infected] I definitely was sick," she said.
"Whereas when I tested positive the second time, I was surprised because I was asymptomatic."
Professor Toole said it was important to remember "if you get infected, don't just think that you're free".
That could mean wearing masks indoors, avoiding crowded events and taking sensible precautions like hand washing, which everyone should be doing anyway, he said.
Gap between infections is also changing
Dr Homaira said the period of natural immunity between infections was shrinking.
"With the previous variants, we saw a much longer period between reinfection," she said
"But with the sub-variant B.A.2 we are seeing there are some data emerging of reinfection between 20 to 60 days.
"There is more reinfection happening more frequently compared to the previous strains, previous variants, so I think the timing is also changing."
At the same time, Australia's national guidelines have extended the so-called immune period, or exemptions from close contact and testing directions.
At the end of March, Australia's health advisory body increased that to 12 weeks, which has being implemented across most jurisdictions in the past few weeks – ACT updated their rules to 12 weeks on Monday.
However, Victoria and the NT have stuck with a more conservative approach and are granting the exemption only for eight weeks after recovering.
Booster may help prevent reinfections
Importantly, Dr Homaira said there was good evidence that the combination of recovering from infection plus a booster vaccine dose gave you the best immune response.
"There has been a staggering falling uptake of the third dose," she said.
"A lot of people are getting infected and they're thinking that natural infection is going to give them immunity, which is not the case.
That also applies to people who might be eligible for a fourth vaccine dose, which currently includes those who are aged 65 or older, in aged or disability care, severely immunocompromised or Indigenous Australians aged over 50.
After her double isolation, Ms Roede is well and back at the gym again.
She just wants others to be mindful that they are not immune to COVID-19 forever.
"I would like to see that number in the daily totals, to actually say how many people were in reinfected, and how many was it their second time getting it."
