Two humans are at least 99.9 percent genetically identical to each other. But it's that 0.1 percent or so that makes us special.

This is what determines all our differences, from the unique ways we look, to our resistance or susceptibility to diseases such as HIV. Certain tiny tweaks in the genetic code can be incredibly helpful not only for the individual, but society.

The more we know about these special genes (and the people who have them) the better, as it might be possible to create drugs that can mimic useful genetic differences.

With that in mind, researchers are searching for people around the world who might be resistant to the SARS-CoV-2 virus. Your genes could hold the keys to potentially treating COVID-19.

"The introduction of SARS-CoV-2 to a naive population, on a global scale, has provided yet another demonstration of the remarkable clinical variability between individuals in the course of infection, ranging from asymptomatic infections to life-threatening disease," a team of researchers, led by immunologist Evangelos Andreakos from the Academy of Athens, writes in a new paper.

"Our understanding of the pathophysiology of life-threatening COVID-19 has progressed considerably since the disease was first described in December 2019, but we still know very little about the human genetic and immunological basis of inborn resistance to SARS-CoV-2."

Although we might not have much information about this inborn resistance, it doesn't mean it doesn't exist. The researchers note that sometimes whole households can be infected, with just a spouse being spared, while there's been other reports of people somehow avoiding COVID even after being in the 'line of fire' multiple times.

There's also been some serious research into this already, but so far, the results have only revealed small differences.

For example, we reported last year that blood type (particularly type O blood) seemed to show a slight resistance to severe SARS-CoV-2 infection. Then there's been other studies looking at proteins such as the ACE2 receptor or TMEM41B that the coronavirus seems to require to either enter or replicate once inside the cell.

The researchers have suggested that we need to be doing more to uncover those secret few in the population who might be genetically resistant to SARS-CoV-2. And they have some ideas about how.

"We propose a strategy for identifying, recruiting, and genetically analyzing individuals who are naturally resistant to SARS-CoV-2 infection," the team writes.

"We first focus on uninfected household contacts of people with symptomatic COVID-19. We then consider individuals exposed to an index case without personal protection equipment, for at least 1 hour per day, and during the first 3-5 days of symptoms in the index case."

This would then be checked with negative PCR tests and negative blood work four weeks after the exposure, particularly looking for T cells to confirm that the person hasn't been infected in the past.

If this sounds like you – good news! The researchers are still looking for participants for their research.

"We have already enrolled more than 400 individuals meeting the criteria for inclusion in a dedicated resistance study cohort," the researchers wrote.

"The collaborative enrolment of study participants is continuing (link here), and subjects from all over the world are welcome."

With vaccines, promising drugs, and more understanding about the virus, we're seeing life – in some places – start to look a bit more normal.

But COVID will likely be with us for a long time yet to come, and finding people who have some genetic way of being spared by the virus could be a real boon for the rest of us – especially if new, highly virulent strains emerge.

This perspective was published in Nature Immunology.