Why do some people get Covid when others don’t?
Holly Ellyatt (CNBC)
One of the great mysteries that has emerged from the Covid-19 pandemic — and one that’s still being investigated by infectious disease specialists — is why some people catch Covid and others don’t, even when they’re equally exposed to the virus.
Many of us know entire households who caught Covid and had to isolate over the pandemic, but there are also multiple anecdotes of couples, families and colleagues where some people caught the virus — but not everyone.
Indeed, Danny Altmann, professor of immunology at Imperial College London, told CNBC that studies indicate the likelihood of becoming infected within a household once one case is positive is “not as high as you’d imagine.”
This could be due to a variety of factors, ranging from prior infection with a similar virus to genetics.
The genetic factor
Why two people with Covid may respond so differently to the infection; one could have heavy symptoms, for instance, and the other could be asymptomatic.
The answer might lie in our genes.
“It’s a really important question,” Imperial College’s Altmann told CNBC on Wednesday.
He said that he and his colleagues have conducted research, to be published soon, into immunogenetics (essentially, the relationship between genetics and the immune system) and Covid-19 infection, and have found that variations between people’s immune systems “makes a difference, at least to whether or not you get symptomatic disease.”
The research is focused on different HLA (human leukocyte antigen) genes and is looking at how these can affect one’s response to Covid, with some HLA types more or less likely to experience a symptomatic, or asymptomatic, infection, he said.
“The key genes that control your immune response are called HLA genes. They matter for determining your response on encounter with SARS-CoV-2. For example, people with the gene HLA-DRB1*1302 are significantly more likely to have symptomatic infection,” Altmann added.