British scientists have identified a gene that doubles the risk of dying from Covid-19, providing new insights into why some people are more susceptible to the disease than others, while opening up possibilities for targeted medicine.

Around 60 per cent of people with South Asian ancestry carry the high-risk gene, researchers at Oxford University said on Friday, adding the discovery partly explains the high number of deaths seen in some British communities, and the effect of Covid-19 in the Indian subcontinent.

Read: India's Covid deaths 10 times higher than reported: study

The scientists found that the increased risk is not because of a difference in genetic coding of the proteins, but because of differences in the DNA that makes a kind of “switch” to turn a gene on.

That genetic signal is likely to affect cells in the lung, while a higher risk version of the identified gene, called LZTFL1, possibly prevents the cells lining airways and the lungs from responding to the virus properly.

However, the higher risk version gene does not affect the body's immune system that makes antibodies to fight off infections, researchers said, adding that those people carrying this version of the gene should respond normally to vaccines.

“(The study) shows that the way in which the lung responds to the infection is critical. This is important because most treatments have focused on changing the way in which the immune system reacts to the virus,” said Professor James Davies, co-lead of the study.

The findings were published in the Nature Genetics journal.

Dr Simon Biddie, an intensive care specialist at the University of Edinburgh, said in a statement that while the study “provides compelling evidence to suggest roles for LZFTL1” in the lungs of patients with severe Covid-19, more research is necessary to confirm the findings.