Written by Charlotte Harrison, Science Writer
Evidence suggests that a person’s genetic make-up may be at least partly responsible for the variation that we see in COVID-19 disease severity amongst the population. This variability occurs once other well-established factors such as age, sex, and comorbidities have been accounted for.
A paper from Jago Bruce and Stephanie Johnson (from the Wellcome Centre for Ethics and Humanities at the University of Oxford) considers if and how a person’s genomics should influence decisions about vaccine allocation.
They use COVID-19 as an example to explore the topic of genomics and vaccine allocation, also noting that these arguments could be applied to other vaccines.
What do we know about genetics and COVID-19?
Current results suggest that changes in specific genes are linked to more severe COVID-19 infections. These include:
- Polymorphisms in ACE2 and TMPRSS2 genes confer significant vulnerability to severe infection.
- The LZTFL1 gene, which has uneven distribution among different geographical populations, is linked to infection severity.
- A rare variant of TLR7 on the X chromosome is associated with a severe COVID-19 response in young men.
It’s likely that as research continues, more information about the role of genetic factors in a person’s response to COVID-19 infection will become available. So, should our knowledge of these genetic factors be used in vaccination programmes?
Prioritizing people at risk of severe disease
It’s accepted that to get the maximum benefit from vaccine allocation, the process needs to benefit people who are more vulnerable to severe disease. The authors’ central argument is that if vulnerability is defined in terms of an increased risk of developing severe COVID-19 for any reason (whether due to underlying medical conditions, social status, or demographical reasons), then genetic risk should be comparable and equal to other clinical and environmental risks.
“Genetic vulnerability should be prioritised in vaccination schemes alongside other kinds of vulnerability, according to the risk conveyed,” say the authors.
The authors note that statistics support the notion that people who are genetically or clinically vulnerable should have similar prioritisation. For example, the risk of severe or fatal COVID-19 due to a certain genetic polymorphism is comparable with that of obesity.
“…discrimination between different types of risk factors is not justified,” they say.
Other points raised in the paper include the possibility of prioritising people for vaccination who have a higher infectivity risk, but low susceptibility to severe disease. In addition, people who are genetically resistant to COVID-19 could be de-prioritised for vaccination. However, the authors note that this latter option may be ethically problematic, especially if applied to healthcare workers, as genomic testing may bring about workplace discrimination.
There’s one huge caveat to this work – we don’t get have people’s genetic data at a population level, or the framework under which this might be used, or know what the public perception of such data will be. Nevertheless, as ethics often has to play catch-up with science (think CRISPR gene-editing), airing a discussion sooner rather than later can’t be a bad thing.
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