Risk of long COVID builds each time you get infected

Recent evidence shows each time you get infected with COVID-19 your risk of getting long COVID increases, Burnet Institute Director and CEO, Professor Brendan Crabb AC has warned.

“What’s happening with COVID in Australia is simply not sustainable,” Professor Crabb told the ABC’s AM program.

“Ten million plus Australians have had COVID this year, and we’ve seen how that’s played out in every facet of our lives.

“In hospitalisations, in an extraordinary death toll – it’s now well over 10,000 – but also for how our businesses operate, travel chaos, schools struggling, getting people back to work.”

Professor Crabb said Burnet modelling has shown that increasing mask use could have a significant impact.

“If increased mask use happened even from July, up to 20 per cent of cases, 20 per cent of hospitalisations and 14 per cent of deaths between July and October could be averted.”

And while you may not know too many people with long COVID now he said, that could all too quickly change.

“Probably about one in 40 or one in 50 of us have long COVID. But by the end of the year that’ll be more like one in 20, unless we put a handbrake on this,” he said.

Already it’s estimated that between 100,000 and 500,000 Australians are going to suffer from long COVID symptoms, Professor Crabb told The MJA Podcast.

“But if we have another 13 million or so COVID infections over the next six months – mirroring the first half of 2022 – that number could double or triple,” he said.

“The best way to address long COVID immediately is to switch to a low transmission strategy.”

Professor Crabb said what drives long COVID are “inflammatory responses gone wrong or gone rogue.

“In one person that can manifest as heart disease, in another kidney failure, in another brain fog.

“That’s what you expect with generalised systemic inflammation – exacerbating what’s already underlying in someone, or causing primary disease in other circumstances.

“It isn’t that virus is getting in and infecting every organ in the body.”

We’re still trying to understand the molecular and cellular basis of these rogue inflammatory responses, but Professor Crabb put forward three possibilities.

“The first being the possibility that there is persistent virus,” he said. “So, you’re getting an immune response to persistent virus attacking and attacking and attacking tissues over a long period of time, even though that virus was very low level.”

A second option could be that the virus leaves a mark that causes the tissue to be infected.

“We call that a superantigen, which is a viral antigen that is able to non-specifically trigger immune responses,” Professor Crabb said.

“Or simply it’s just our immune response from an acute infection that never slows down, and just keeps going.”

Understanding the underlying factors causing long COVID will reveal solutions as to how to best treat it.

What makes SARS-CoV-2 so good at causing us problems is that it “can evolve to go into battle and to win against our very sophisticated immune responses”, Professor Crabb said, and that’s partly what’s happening with long COVID.

“There are these symptoms, they’re very real,” he said.

But for Professor Crabb the most worrying part of the evidence emerging in recent times is that each time you get infected with COVID-19, your risk of also getting long COVID increases.

“Each time you’re getting infected, both the acute and the chronic risk is increased. We just can’t have that,” he said.

“I’m not so worried about really severe disease. I am personally concerned for me and my family more about long COVID.”

Click here to listen to The MJA Podcast episode in full.

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