Scientists believe they have finally solved the secret of why some people who have contracted Covid never get sick again.
And the answer lies in their genes.
The researchers discovered that the “super cheaters” had mutations in their DNA that allowed their immune systems to recognize the virus as a cold.
This meant they could flush out the Covid early before it could run rampant and make them sick, unlike people without the mutated gene.
Carriers of the oddity were eight times less likely to contract Covid, according to a genetic analysis of 1,500 people.
Nassim Foroughi, 46, a cardiac research nurse at St Bartholomew’s Hospital in central London, was heavily involved in research to trace Covid among frontline staff – a role that potentially exposed her to hundreds of infected people since the pandemic began in early 2020. But she never caught the virus
It is estimated that only about one in ten people in the general population possess the genes that offer them this form of protection.
The mutations in question change the way the human leukocyte antigen (HLA) works.
The protein marker marks threats to the body’s immune system for disposal.
As a result of the genetic quirk, the immune cells were able to recognize Covid – even though it was foreign to them.
In comparison, normal people’s immune systems had to learn how to recognize the virus from scratch, by which time it was already spreading inside them and making them sick.
Professor Jill Hollenbach, an epidemiologist at the University of California and lead researcher on the new study, said the mutation gives some people a huge advantage against Covid.
“If you have an army that is able to recognize the enemy early, that’s a huge advantage.
“It’s like having soldiers who are prepared for battle and already know what to look for, and that those are the bad guys.”
The researchers used data from the US Citizen Science Survey of Covid-19 and the US Bone Marrow Registry to find people who tested positive for Covid, whether or not they had symptoms.
The analysis identified 1,428 people who tested positive between February 2020 and the end of April 2021.
Scientists used this period as it was before Covid injections – proven to help patients fight the disease – became widely available.
Of the participants, the experts found 136 individuals who were asymptomatic, meaning they did not suffer from symptoms of the virus, at least two weeks before and after a positive test.
The analysis revealed that people with the altered HLA protein were eight times more likely to avoid contracting Covid than those without the mutation.
Further work, this time led by Australian scientists, also revealed why the altered HLA was better able to recognize Covid as a threat.
Professor Stephanie Grass, a biochemistry expert at La Trobe University in Melbourne, said the immune cells with the mutation were found in a part of the structure of the Covid virus called the NQK-Q8 peptide.
She explained that this is a part of the virus very similar in composition to a structure called the NQK-A8 peptide carried by cold viruses, and it allows the immune system to mark the virus as a threat.
The research, published in the journal Nature, not only answers questions about the pandemic and how some people avoided getting sick.
Professor Grass said it could also be used to potentially develop new treatments.
“By studying their immune response, it may allow us to identify new ways to promote immune defense against Sars-CoV-2 that could be used in future vaccine or drug development,” she said.