PARIS: People who have a particular genetic variant are twice as likely to never get sick when they contract Covid-19, researchers said on Wednesday, offering the first potential explanation for the lucky group dubbed the “super dodgers”.

Those who have two copies of the variant are eight times more likely to never get any symptoms from Covid, according to the study in the journal Nature.

Previous research has suggested that at least 20 per cent of the millions of Covid infections during the pandemic were asymptomatic.

To find out what could be behind these cases, researchers took advantage of a database of volunteer bone marrow donors in the United States.

The database included each person’s type of human leukocyte antigen (HLA), which are molecules on the surface of most cells in the body.

The immune system uses HLA to see which cells belong in the body, and they are thou­ght to play a key role in the response to viral infections.

The researchers had nearly 30,000 people on the bone marrow registry self-report their Covid tests and symptoms on a mobile phone app.

More than 1,400 unvaccinated people tested positive for Covid between February 2020 and late April 2021, the study said.

Out of that group, 136 saw no Covid symptoms two weeks before and after testing positive. One in five of that group carried at least one copy of an HLA variant called HLA-B*15:01.

Those fortunate enough to have two copies of the gene — one from their mother, one from their father — were over eight times more likely to be asymptomatic from Covid than other people, the study said.

To find out why this was the case, the team carried out separate research looking at T cells, which protect the body from infections, in people who carried the variant.

Published in Dawn, July 20th, 2023