During the early days of the pandemic around 3.5 per cent of people who caught Covid-19 in the UK required hospitalisation. Many studies have highlighted the importance of factors such as age, weight (or body mass index) and existing conditions to an individual’s risk of infection, hospitalisation and death. But it also turned out that the picture was more complex.
From the earliest days of the pandemic, there was an explosion of large studies trying to understand how our genetics might help explain the virus’s diverse and often mysterious disease trajectory. One such effort was from a global consortium of doctors and scientists known as GenOMICC, which had already been looking into genetic determinants of severe illness following infection.
Over the first two years of the pandemic, tens of thousands of samples were taken from critically ill Covid patients, many from intensive care units. Analyses were then conducted to try to identify genes that might be associated with the worst patient outcomes. Severe responses to Covid-19 often involve a total breakdown in normal immune signalling. This can result in a dangerous influx of normally helpful immune cells and proteins into the sites of infection (lungs, in this case). It is therefore not surprising that many of the 49 genetic variants identified as being associated with critical illness from Covid code for proteins involved in immunity.
In May, in the journal Nature, GenOMICC reported finding links between severe Covid and a wide range of genes and their patterns of activity. Encouragingly, some are already known targets of existing drugs that could potentially be repurposed for treatment of severe Covid. The report also identified an association between severe illness and multiple genes involved in how the virus actually enters the patient’s cells. These findings provide useful insights into how an individual’s route to infection, as well as their biological response to it, may determine why some people get critically ill with Covid, whilst close to a third of us have no symptoms at all.
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