Jacinta Bowler
With an estimated 8 in 10 Australians already having had COVID-19, it’s something many don’t want again any time soon.
But how likely are you to get COVID-19 after being infected? And is the infection the second time round less or more severe?
A meta-analysis published in The Lancet tried to answer these questions.
How likely are you to get COVID-19 twice?
The Lancet paper looked at 65 individual studies from 19 countries and split up ‘protection’ into categories of strains – the original or ancestral strain, as well as the variants Alpha, Beta, Delta and Omicron BA.1.
These results are all normalised to provide information for 10 months after the original infection.
In Australia most COVID-19 is being caused by the ‘scrabble’ variants – most commonly XBF. They are a version of Omicron but slightly different to Omicron BA.1 discussed in the paper.
Therefore, you should assume that your protection from reinfection is likely (at best) the levels of Omicron.
The paper compares people who have never had COVID-19 with those who have been infected once, and concludes infection gives a person immunity, roughly in line with a vaccination – they are about 45% less likely to get Omicron BA.1 a second time compared to a person who has never had the disease.
Rates for all other variants was 82-90%.
Is it going to be worse the second time?
The paper also tracked whether the person got ‘severe disease’ if they contracted the disease a second time round.
Severe disease in this case means either hospitalisation or death. It, unfortunately, doesn’t include any really bad cases that were managed at home.
The news here is significantly better. The team found that a prior infection from any variant or strain led to a high amount of protection against severe disease a second time round – between 78 and 97%. That includes Omicron BA.1 at 82%.
That means that for most people the chance of getting hospitalised with a second bout of COVID within 10 months is very low.
“The fact that your risk of severe disease is greatly reduced on re-infection with COVID-19 is great news. However, the ongoing spreading of the virus is still problematic as it still leaves vulnerable populations at risk and it allows the virus to continue and mutate into newer variants,” says Garvan Institute of Medical Research immunologist Dr Deborah Burnett.
Read more: COVID-19 immunity doesn’t seem to be working well enough to manage the pandemic, says Burnet Institute head
Should I get vaccinated?
The paper makes the interesting point that having COVID-19 once gives you pretty good protection from getting it again – at least as high than two doses of vaccination.
“Although protection from re-infection from all variants wanes over time, our analysis of the available data suggests that the level of protection afforded by previous infection is at least as high, if not higher than that provided by two-dose vaccination using high-quality mRNA vaccines,” the researchers write in the new paper.
Of course, it’s important to note that this doesn’t mean people shouldn’t get vaccinated – particularly if they’ve never had a COVID infection. For most people vaccination creates immunity without severe illness, so it is by far the best and safest way to ensure your body is building immunity to COVID-19.