There is a lot to learn from studies like this and it is quite exciting.

In a world's first challenge trial done at the height of the pandemic researchers in the U.K. infected dozens of healthy unvaccinated adults with a low dose of the original coronavirus.

Then closely tracked how long it took their immune system to kick in.

Participants who were infected right away had a slow response.

In those who became infected but quickly cleared the virus it was faster.

But those who never became infected had the fastest response.

Researchers noted high levels of activity in a specific gene called HLA-DQA2.

Scientists think it helps flag viral invaders to the immune system so quick it destroys them before they can replicate.

This work is really special in the point in the middle.

Immunologists say they're still not sure how or why that specific gene offers protection.

If you would ask me to bet money on what the genes that were going to be involved with the protection these are not the ones I would have chosen.

I feel lucky.

We met Hugh Potter in 2022.

He was exposed to COVID through his wife but never got sick.

His DNA is part of ongoing research.

Potter now wonders if that gene's protecting him.

They do have a gene which could mean in the future possible cures for people from maybe more than just the virus.

Doctors who've been collecting DNA samples from people like Potter say while the UK study is helpful there are more genetic secrets to unravel.

It puts an anchor in the ground and says we got to look at this and everything around it so that's how these major discoveries are made.

All of the scientists we spoke with said while there are new variants and much more research is needed this gene could help invent new vaccines to target COVID and possibly other respiratory viruses too.

Christine Birak, CBC News, Toronto.