Wed. Aug 10th, 2022

Early research suggests that if you catch COVID-19 more than once, you’re more likely to face serious health issues.

Re-infections of the virus are on the rise in Australia following the growth of two sub-variants of Omicron, BA.4 and BA.5, which are expected to soon become the most dominant COVID-19 strains.

There had been hope that the health risks associated with contracting COVID-19 would decrease with subsequent infections.

But Nancy Baxter from the School of Population and Global Health at Melbourne University said early research, based on data collected from the US Department of Veterans Affairs database, showed that was not the case.

The research, which is yet to be peer reviewed, shows that while there are some benefits to immunity from contracting the virus, the chance of negative health impacts increases with each successive infection.

“You continue to have a risk of things like problems with your breathing, breathlessness, problems with your heart, long COVID and… having a higher risk of death than you would be expected to have,” Professor Baxter said.

“Which means that the more times you get it, the more is going to be added to the chance that you’re going to at some point have experienced a really negative consequence of having COVID-19.”

What’s more, the benefits to immunity from contracting the virus wane over time, making re-infections increasingly likely.

“For the first month and probably extending to the first couple of months after you’ve had Omicron, you have some protection against getting it, but then it rapidly declines,” Professor Baxter said.

While the study included more than 5.5 million people, only 10 per cent (566,020) were women, leaving potential for inaccurate representation in a more balanced population.

A woman poses against a colorful background for a portrait
Nancy Baxter, head of the Melbourne School of Population and Global Health, said it’s important for people to get their booster shot.(Supplied)

Dr Deepti Gurdarasani from Queen Mary University of London agreed that while the research has some caveats, its findings have significant implications for the way we think about COVID-19 re-infections.

“It’s clear that the ‘re-infection is benign’ or ‘mild’ narrative does not really hold,” she said on Twitter.

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Gap in Australian data

In Victoria, more than 20,000 reinfections have been recorded through data-matching processes.

In New South Wales, that figure is more than 11,300, nearly half of which occurred after the Omicron variant emerged last November.

But Professor Baxter said those numbers were a significant underestimate.

“The figures that we have aren’t great because re-infection isn’t being recorded well, particularly because now they’re not allowing you to record a second infection with COVID-19 if you’ve had it within four months.”

COVID-19 infections under reported

The official number of daily COVID-19 infections is around 30,000, which is much lower than the peak in early 2022 of more than 100,000.

But Professor Baxter warned that the official figures were also a significant underestimate.

“We do not think that they are being recorded with the same kind of level of accuracy that they may have in the past,” she said.

“We know that PCR tests are harder to get, not everyone’s recording their rapid antigen tests and not everyone’s even doing COVID-19 testing.”

With mask-wearing declining and community immunity from the January peak waning, Professor Baxter said she expects infections and deaths to continue to increase.

“We had a period of about six weeks where the numbers were gradually declining. Now we’re seeing a reverse of that trend where the numbers are increasing again,” she said.

Professor Baxter echoed other epidemiologists who have called for a greater focus on mask wearing and air filtration to reduce transmission.

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