The £130 first-of-its-kind test to check you chance of getting severe Covid
- New test uses a saliva sample to calculate an individual’s odds of severe Covid
- First test of its kind combines information on genes linked to the virus’s severity
- To develop the £130 test, scientists in Australia compared thousands of patients
Would you want to know if someone could tell you how likely you were to end up in hospital with Covid-19?
That’s the tantalising information being offered by a new genetic test which uses a sample of saliva to calculate an individual’s odds of severe Covid.
The first test of its kind, it combines information on genes linked to the virus’s severity with details of a person’s age, sex, weight and general health to estimate their ‘personal risk of severe disease’.
A new genetic test uses a sample of saliva to calculate an individual’s odds of severe Covid
To develop the £130 test, scientists in Australia compared 2,200 Covid patients whose symptoms had been severe enough for them to be admitted to hospital with another 5,400 who had tested positive for the virus but had only mild or no symptoms.
They looked at how likely the volunteers were to have 100 or so genes that have been linked to Covid severity in other studies carried out around the world.
While it isn’t known exactly how our genes affect our risk, one, identified by a team at the University of Edinburgh, is thought to affect the body’s ability to fight off Covid by ‘chewing up’ the virus’s genetic material.
Another gene spotted by the same researchers may affect how well protective proteins called interferons get to work.
Close-up of young man getting PCR test at doctor’s office during coronavirus epidemic
The Australian team zeroed in on seven genes with strong links to severe Covid and, combining this with personal information and details of existing health conditions such as diabetes, high blood pressure and respiratory problems, were able to predict with 73 per cent accuracy who was at risk of severe Covid, according to a report published in June in the journal Epidemiology and Infection.
‘We were able to pull apart the risk factors, then use them to work out exactly who would be at high risk and who would be at low risk,’ says Dr Gillian Dite, a senior biostatistician at the company Genetic Technologies, which invented the test.
The test itself involves simply spitting into a tube and sending off the saliva sample for genetic analysis.
The genetic data is then combined with personal and medical information that you enter online, to provide a prediction of how likely you are to end up in hospital if you catch Covid — and how you compare with other people of the same age.
For example, you might be told you had a 12.7 per cent ‘probability of hospitalisation’ and that this is higher than three in four adults of your age.
Some results are surprising. For example, poor health, obesity and genetics can mean a man in his 50s is three times as likely to develop severe Covid as a woman who is 30 years his senior but of normal weight, free of underlying health conditions and with ‘good’ genes.
However, some experts have questioned how much added value the genetic data gives, over and above information on a person’s general health, age and sex, all of which is already at hand.
‘It isn’t clear how much extra predictive power it adds to include the genetic information on top of information that is much easier to obtain about people’s age, sex and whether they have certain clinical conditions,’ says Kevin McConway, an emeritus professor of applied statistics at the Open University.
He also points out that the test was developed using data from before the Delta variant of Covid became dominant.
This means it isn’t clear how relevant predictions are for people who catch the virus today.
Furthermore, the results are based on a person’s risk if they haven’t been vaccinated. Vaccination is known to cut the chances of admission to hospital by up to 96 per cent.
Poor health, obesity and genetics can mean a man in his 50s is three times as likely to develop severe Covid as a woman who is 30 years his senior but of normal weight, free of underlying health conditions and with ‘good’ genes
The company says the results might persuade some of those who are hesitant about being vaccinated to have the jab.
And someone who has been vaccinated but has a ‘high-risk’ readout might decide to take precautions such as avoiding crowded places.
While nationally about 80 per cent of people aged 12 and over have had two doses of the vaccine in the UK, in some parts of London the rate is as low as 50 per cent.
The theory is that finding out you are at high risk of severe Covid may provide an incentive to get immunised against it.
But Dr Simon Clarke, a microbiologist at the University of Reading, cautions that the test could also have the opposite effect, with a low-risk result making some of those who are unvaccinated even more reluctant to get jabbed.
He adds that while being told you are at high risk ‘might make you more careful in terms of social distancing, the jury is still out in terms of the accuracy of tests like this’.
The test is now available in the U.S. via mail order, and the company is ‘looking to make it available in the UK in the coming months’.
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