While most people with COVID do not end up in hospital due to their condition, some suffer from a more severe form. It was evident that COVID was more common in minority groups than it was among whites from the beginning of the first wave.
Socio-economic factors play a part in this higher risk. People of minority origin in the UK are more likely than whites to live in crowded areas and are more likely live in multi-generational homes. This means that older people are more susceptible to the spread of viruses to younger family members.
They are also more at risk as they work in care homes and healthcare facilities, which increase their vulnerability to the virus. However, this is only part of the story.
In a large study, The Lancet published a May 2021 report that found that the risk of dying, being hospitalized or needing intensive care from COVID in England was higher for people of mixed and Asian origins than it was for white people in the UK's first pandemic (spring 2020).
The risk for Black and mixed-ethnic groups declined in the second wave. However, it was the reverse for south Asians. They were at greater risk of dying from COVID or ending up in hospital than whites and other minorities.
This could explain the difference. Could this be because certain ethnicities are more susceptible to severe COVID?
Two questions
In 2020, genetic studies proved that there were genetic differences that could lead to severe COVID. Researchers discovered two possible suspects in the genetic studies of thousands of COVID sufferers: SLC6A20 and LZTFL1.
The questions to be answered were: Which one of these genes increases the risk for severe COVID? How does it do this?
The answer is in a new Nature Genetics study.
Researchers from Oxford found that LZTFL1 is responsible for higher severity diseases, not SLC6A20. The higher-risk variant of the gene is found in 60% of those of South Asian descent, compared to 15% for whites and 2 percent for people with African or Afro-Caribbean backgrounds.
This gene is also active in the cells that line the lungs and airways. The respiratory epithelium is a layer of cells that warms and cleans air before it reaches lungs where it is absorbed into blood.
It is vital for healthy breathing because it acts as a barrier between air entering the respiratory system from the body's inner tissues and the air that comes in through the nose.
The high-risk variant of this gene is less able to repair damaged tissue or replace cells that have been lost. This could be a sign of severe disease.
Cells with the variant have more copies (called ACE2 or TMPRSS2) of two proteins that allow the SARS virus to enter cells and infect them. This means that high-risk variant carriers are more likely to have more infected cells, less healing ability, and a more severe infection.
We don't know yet how significant COVID's impact on UK residents of south Asian descent is. However, these findings do not mean that socioeconomic factors haven’t played an important part.
We don't have any data yet on the role the gene might play in South Asian countries, where there are more people likely to be affected. This could also impact efforts to combat the pandemic.
The results of this study, however, are significant because they reveal that there is a biological component to the higher risk among certain ethnic groups such as those of south Asian heritage.
There are currently drugs and vaccines to treat COVID. However, this new study suggests a way to develop new treatments that target the lung rather than the immune system. This is what has been most of the attention so far. This could prove especially useful for people at high risk of serious diseases.
Ana Valdes, Professor of Molecular and Genetic Epidemiology at the University of Nottingham
This article was republished by The Conversation under Creative Commons. You can read the original article.
