Commentary: Genetics might explain why some people have never had COVID-19

IS IMMUNITY IN THE GENES?

The COVID Human Genetic Effort, led by researchers in the US, has recruited people with known exposure to the virus, but who haven’t had it themselves. This includes, for example, healthcare workers or people who lived in a household with a confirmed case of COVID-19.

Scientists will be examining their DNA and looking for unusual mutations that may explain an apparent resistance to SARS-CoV-2 infection. This may be a mutation in the cellular receptors or enzymes needed for the virus to gain entry to our cells, or perhaps a mutation in a gene involved in the immune response to infection.

Studies that look to uncover anomalies in our DNA, termed genome-wide association studies, have already been able to identify genetic mutations that make some people resistant to other infections like HIV and norovirus (the winter vomiting bug). If we can identify the reasons people may be immune to a particular virus then, theoretically, that knowledge could be used to prevent the infection.

But is it really that simple? Despite our understanding of the genetic mutations that protect a lucky minority of people against norovirus, there’s no vaccine or treatment for this virus. And the infamous “CRISPR babies” (several children born in 2018 whose genomes had been edited in an attempt to make them immune to HIV), received criticism for dubious ethics, not to mention being illegal.

It’s possible that it’s not a mutation in one gene, but a combination of mutations in multiple genes, that render a small number of people immune to COVID-19. Targeting multiple genes without causing any unwanted side-effects can be tricky and would make it much harder to harness this knowledge for anti-COVID-19 drugs.

But understanding the genetic mutations that make someone resistant to COVID-19 could provide valuable insight into how SARS-CoV-2 infects people and causes disease. In other words, it may be interesting scientifically, but perhaps not clinically.

While it will be some time before we have answers from these studies, scientists do believe there is a small group of people who are naturally immune to SARS-CoV-2 owing to their genes.