Why are more Aussies getting reinfected with Covid?

New figures show almost half of Australians have had Covid, and many say they’ve battled the virus multiple times. Here’s what to expect if you get reinfected.

Two years into the pandemic, people are catching Covid, not for the first time, but rather their second or third time.

Ann, her husband Ken and their son Angus caught Covid in Melbourne back in March 2020.

Ann and Angus experienced flu-like symptoms for a couple of days.

But Ken ended up in hospital for five days with breathing difficulties.

“It was quite scary, just because of all the unknowns at that time, the staff were in full PPE gear, it was really confronting,” Ann says.

After they recovered, the family hoped they had developed some immunity to Covid, but they also got vaccinations and boosters as soon as they were eligible.

However a couple of weeks ago, the family tested positive for Covid again.

“I feel like we drew the lucky straw this time around, it was really like just having a head cold for a couple of days, after that we were all pretty much ok,” Ann says.

“It really does raise the question, how long do you have immunity for?”

Are more people getting reinfected with Covid?

Professor Cassandra Berry from Murdoch University Viral Immunology says most cases of Covid reinfection are due to the new Omicron sub-variants circulating in the community.

“In Australia, the dominant strain is BA.4 and BA.5, but BA2.75 has also just arrived,” Prof Berry says.

Prof Berry says it is likely reports of Australians reinfected with Covid are actually underestimated and this will change quickly over the next few months as the sub-variants spread.

Australian National University ARC future fellow Dr Benjamin Schwessinger says the new variants have been shown to have better “immune escape” than prior Omicron infections.

“As new variants emerge, they are better at evading pre-existing immunity, especially if it’s been a while since the last vaccination or infection,” Dr Schwessinger says.

How long do you have immunity for after getting Covid?

The Australian government recently announced the Covid reinfection period has been reduced from 12 weeks to just 28 days, but Dr Schwessinger says it is hard to say how soon reinfections can occur.

“This depends on so many things like strength of immunity, the infecting variant and the type of variant that you have immunity against,” Dr Schwessinger says.

“It can also be hard to detect a reinfection – is it just residual virus from the first infection or is it a true new infection?”

A Harvard Medical School study from July 2022 found previous infection from Covid, or having been vaccinated, does not provide as much protection against the BA.4 and BA.5 variants, compared to the original coronavirus strain.

What can I expect if I get reinfected with Covid?

Dr Schwessinger says studies have found Covid reinfection generally tends to be less severe.

Prof Berry agrees, saying most people can expect a milder case with Omicron strains.

But she warns if a new variant of concern emerges the severity may change.

“It is important to respect the virus and don’t become too complacent,” Prof Berry says.

“Anyone at any age, even those without risk factors or comorbidities, may require hospitalisation and face death.”

Will boosters help make Covid reinfection less severe?

Prof Berry says keeping up to date with boosters, even if they are not Omicron specific, has a number of benefits such as:

  • Increasing antibody levels
  • Improving protection
  • Reducing post-viral complications

“We cannot afford to wait until next year for the new Omicron specific vaccines,” Prof Berry says.

“Getting boosters will also help our hospital case load management during this winter wave.”

Dr Schwessinger agrees, saying a fourth dose boosts our antibody levels which can help rapidly neutralise any virus particles entering our body.

“While vaccine antibodies may be ‘less’ effective at neutralising newer variants … compared to the ‘original’ variant, they are still effective, and having more antibodies around will maximise our protection,” Dr Schwessinger says.

Written by Bianca Carmona.