Overcoming COVID
Early in the pandemic, research by the COVID Human Genetic Effort, the international consortium that Dr. Spaan is part of, linked severe COVID-19 pneumonia to the lack of immune molecules known as type I interferons and to antibodies produced by the body that destroy these molecules. Together, these mechanisms explain about one-fifth of severe COVID-19 cases, the researchers reported in 2021.
A few studies by other groups have explored resistance to COVID-19 infection, suggesting that reduced risk of contracting the virus is tied to certain blood group factors. People with Type O blood appear to be at slightly reduced risk of infection, for example.
But the studies done so far are designed to find common genetic variations, which generally have a small effect on resistance. Now, genetic researchers are launching an effort to identify genetic resistance factors with a big effect, even if they are vanishingly rare.
The group is recruiting people who did not become infected with COVID-19 despite heavy exposure, such as those living in households where all the other members got sick or people who were exposed to a superspreader event but did not become ill. As with tuberculosis, being certain that someone has not been infected with the virus can be tricky, but the team is using several blood tests to home in on the people most likely to have escaped infection.
They plan to sequence the genomes of these people to identify things that strongly affect infection risk, then do more laboratory studies to try to tease out the means of resistance.
Their work is inspired by earlier efforts to uncover inborn resistance to infections, Dr. Spaan says. Despite the lack of known examples of such resistance, he is optimistic about the possibilities. Those earlier efforts took place in “a different epoch,” before there were rapid sequencing technologies, Dr. Spaan says.
“Now we have modern technologies to do this more systematically.”
The emergence of viral variants such as the Delta and Omicron COVID strains raises the stakes of the work, he continues.
“The need to unravel these inborn mechanisms of resistance to COVID has become even more important because of these new variants and the anticipation that we will have COVID with us for years.”
A version of this article first appeared on WebMD.com.