Study into gene that affects Covid severity should be treated with caution

The statistics are stark. In the second wave of the pandemic those with Pakistani backgrounds were more than twice as likely to die from Covid-19 than those from white European backgrounds. For those of Bangladeshi heritage the risk was three- to four-fold.

The disproportionate impacts of the pandemic have required policymakers to confront the question as to why some people have experienced far worse outcomes than others.

Now, it seems, part of the explanation could be genetic. A gene has been found that alters the way that cells in the lining of the lungs respond to the Covid-19 infection.

If you carry the low-risk genetic variant your cells will be quicker to batten down the hatches against the virus. With the high-risk gene this defence mechanism is more sluggish, doubling risk of respiratory failure and death.

The University of Oxford scientists behind the study estimate that the high-risk gene is carried by about 60% of those with south Asian heritage, compared with 15% of those with white European backgrounds and just 2% of those with black African or Caribbean heritage.

The findings offer a plausible explanation for the continued unexplained risk in south Asian populations in the UK. For those of black African heritage – a group particularly badly affected during the first wave – almost all the additional risk could be explained by factors such as occupation, underlying health problems and place of residence. And outcomes for this group were far better during the second wave.

This was not the case for those of south Asian heritage. According to ONS data, once socio-economic factors were accounted for, those of Indian, Bangladeshi and Pakistani backgrounds still had a 50% increase in risk, which scientists had struggled to explain.

While the genetic explanation for this continued disparity is plausible, it needs to be treated with caution. First, the finding needs to be confirmed, ideally using genetic data from Covid patients from different ethnic backgrounds. It also serves as a reminder that those from ethnic minority backgrounds are not fairly represented in the vast genetic databases which underpin many discoveries about the role of genes in health.

The claim that the LZTFL1 gene is present in 60% of those of south Asian backgrounds and 2% of those with an African background derives from a database of nearly 200,000 genomes, 85% of which come from those of European descent.

Without better representation in these databases, scientists cannot be confident that these figures apply across whole swathes of society – especially because social definitions of ethnicity rarely map neatly on to the distribution of risk genes through the population.

Even assuming that genetics explain a proportion of risk, this must not be used by policymakers to abdicate responsibility. For south Asian populations, socio-economic factors still play a more substantial role. Factors such as workplace exposure to infection and the impact of infections running sky-high in school-age children in multi-generational households need to be considered.

There are also policy implications if the genetic finding is confirmed, such as potentially offering booster vaccines to those of south Asian backgrounds on a priority basis.