An international study involving Irish researchers has provided new insight into why Covid-19 affects people so differently.

It is hoped that these findings may help in the development of new therapeutic strategies to treat the virus which has so far killed over 6.6 million people worldwide.

The work was carried out by researchers from Institut Pasteur in Paris, St James’s Hospital in Dublin and Trinity College Dublin (TCD).

As part of this work, they discovered a link between very sick people and their difficulty or inability to produce a key anti-viral protein called type 1 interferon.

Earlier studies, some of which were worked on by members of this collaboration, had already shown that if type 1 interferon was compromised, then viral infection would not be cleared. This new work builds on this, helping to explain why simply administering type 1 interferon therapeutically has been largely ineffective.

The researchers found that when type 1 interferon was added to the blood of patients with severe Covid-19, their immune cells were much more inflammatory as compared to people who had much milder Covid-19. 

According to the study’s senior investigator, Darragh Duffy of the Institut Pasteur, it has long been known that people respond very differently to Covid-19, with some remaining relatively well or even being asymptomatic, while others get very sick or die as a result.

“But we are still hunting for a more complete picture of why this is the case. This latest research has added more layers to our understanding and the results are exciting as they may help explain why therapeutic use of type 1 interferon late in infection has failed despite many studies showing how important this protein is in early infection,” he explained.

These latest findings support interferon testing much earlier in the disease course. They also reinforce the need to screen individuals with compromised responses, either due to genetics, autoantibodies or treatments, for complications with Covid or other acute viral infections.

“This study reveals important new insights into why inadequate and inappropriate type I interferon responses can be so detrimental in severe Covid-19, which helps us to understand more about the early biological immune processes that go wrong in people with severe disease,” commented Dr Nollaig Bourke of TCD.

The findings are published in the journal, Nature Communications, and can be viewed here.