A new study published in the science journal Nature has revealed why some people never get COVID-19, even after exposure. Researchers conducted a world-first experiment where they intentionally infected healthy volunteers with a pre-Alpha strain of SARS-CoV-2.
They found that people who resist infection have a much faster immune response in their nasal tissues compared to those who get sick. This response includes the activation of mucosal-associated invariant T (MAIT) cells and a drop in inflammatory white blood cells, which clear the virus before it sets in.
The study also found that people who resist infection have elevated expression of a gene called HLA-DQA2 in nasal cells.
Professor Christopher Chiu, from the Department of Infectious Disease at Imperial College London, and who led the COVID-19 human challenge study, said: "This paper highlights the value of the powerful, cutting-edge approaches applied through collaboration in the first-in-the-world SARS-CoV-2 human challenge study.
"This programme of research continues to provide unique insights into how the immune system protects us from infection that cannot be achieved in any other setting.
"Not only will these findings have an important impact on the development of next-generation interventions for SARS-CoV-2, but they should also be generalisable for other future outbreaks and pandemics."
This research could provide a basis for developing new treatments and vaccines that mimic these natural protective responses.
