British scientists have identified a gene that doubles the risk of dying from Covid-19, opening up possibilities for targeted medicine and providing new insights into why some people are more susceptible to the disease than others. Researchers at Oxford University found that 60% of people with South Asian ancestry carry the high-risk gene. The discovery partly explains the high number of deaths seen in some British communities, and the effect of Covid in the Indian subcontinent. 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. 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.