Black and Asian people may be at greater risk of more severe illness from coronavirus due to social, cultural and biological reasons, experts have said.

Data on patients with confirmed Covid-19 from the Intensive Care National Audit and Research Centre (ICNARC) shows that ethnic minorities are over-represented compared with the general population.

Of 1,966 patients with Covid-19, the ICNARC said 64.8% were white, 13.6% were black, 13.8% were Asian, and 6.6% were described as other.

Duncan Young, professor of intensive care medicine at the University of Oxford, has pointed out that in the UK 2011 census, about 7.5% of the population were Asian and 3.3% black.

He said that in patients with non-Covid viral pneumonia treated on ICUs in the past, the proportions of Asian and black patients were similar to the population.

According to the ICNARC, data on patients with viral pneumonia from 2017-2019 showed 2.7% were black and 5.7% were Asian.

Prof Young said: "There are reports from the USA about far more than expected black patients being hospitalised for Covid-19.

"There is a possibility of a genetic cause for the disproportionate number of ICU admissions in Asian and black patients, but as it is occurring across two different ethnic groups this is not likely.

"The larger-than-expected numbers of cases in Asian and black patients may represent an effect of different social or cultural factors leading to more cases in these groups overall that is simply being reflected in ICU admissions.

"Alternatively, it may be the burden of chronic conditions predisposing to severe Covid infections and hence ICU admission is higher in these ethnic groups."

Dr Riyaz Patel, associate professor of cardiology at University College London, said: "The observational data so far do seem to suggest that black and Asian patients are at greater risk of more severe illness from Covid-19.

"As others have suggested, this could be because of socioeconomic factors, with BME patients more likely to live in densely populated areas, multi-generational families in the same household and having more public-facing jobs, all of which makes the likelihood and duration of exposure to the virus more likely.

"Another explanation is that the virus has so far hit densely populated areas like London first, where BME populations are high.

"Most of the data from the ITUs so far comes from big London centres. As such, as time goes on we may see a levelling off of the racial disparity as the rest of the country is affected.

"Nonetheless, there could be biological reasons for the difference which we can speculate on.

"One thing very visible to us in London ITUs now is how diabetes, high blood pressure and possibly being a little overweight seem to be such potent risk factors for having a severe lung illness, perhaps even more so than having an existing lung disease which you would think would be a greater risk.

"All of these risk factors are more common in black and Asian patients, so there could be a link here which needs further exploration."

By Catherine Wylie, PA