The battle against Covid-19 is taking place on many fronts.
In the mix of clinicians, scientists and innovators taking up the challenge are the immunologists who focus on the body's own capacity to fend-off dangerous invaders.
Prevention is the best defence, but if the novel coronavirus finds a way in, a person relies on their immune system to fight it off - or not.
What is it about some people's immunological response that allows them be infected and show no, or only mild, symptoms, while for others, the consequences can be fatal?
Decoding the immunological signature of coronavirus patients is the focus of an academic medical research team working between Trinity College Dublin (TCD) and St James's Hospital, Dublin.
It is one of several key Covid-19-related studies in which Trinity immunologists and infectious disease specialists are engaged.
In this one, they are gathering blood and nasal swab samples from all patients with the disease admitted to St James's and are hoping for a breakthrough in the short term.
The project is being led by Cliona Ní Cheallaigh, infectious disease consultant at St James's, and Cliona O'Farrelly, professor of comparative immunology at Trinity BioSciences Institute.
Prof O'Farrelly said the group was "looking for markers of the patients who will have a catastrophic response to infection and markers of those who will have a quick, effective and protective immune response".
She said there was a realisation that a lot of people who got infected did not get that sick and "it is something to do with their immune system. We are trying to find what is different about immune systems of people who have catastrophic responses".
Already preliminary results are showing that patients who require ventilation have altered immune cells and raised levels of some immune proteins in their blood.
"It would be really useful," Prof O'Farrelly said, "if we can identify which patients will not have a catastrophic response because then they can be sent home quicker and free up hospital beds for those who become dangerously ill."
Ultimately, success could also help in the search for an effective vaccine and new ways of treating the disease.
Prof O'Farrelly, whose background is in human immunology, is currently leading a Science Foundation Ireland (SFI) project into women who were exposed to the contaminated anti-D immunoglobulin in the 1970s but who did not get infected.
But it was one of her students, Dr Liam Townsend, a clinical fellow on the Wellcome-Health Research Board (HRB) Irish Clinical Academic Training Programme (ICAT), who inspired the Covid-19 study.
She and Dr Ní Cheallaigh are co-supervising his PhD.
Dr Townsend, a registrar in infectious diseases at St James's, tweeted: "One of the hardest aspects of managing #COVID patients is that it's the first serious illness I've come across where I have no effective intervention to offer other than calling my critical care colleagues."
He was already looking to his specialism for answers and, according to Prof O'Farrelly, "he was saying we should be looking for the immunological signature of people who have a catastrophic response".
The research team, which also includes Dr Nollaig Bourke, Dr Colm Bergin, Dr Jean Dunne and Dr Niall Conlon, got fast-tracked ethics approval to carry out their patient study and support from the Dean of Research at TCD and the Trinity Translational Medicine Institute.
The work has been greatly assisted by Trinity's collaboration with Dr Darragh Duffy from the internationally renowned Paris-based Pasteur Institut, which has sent over specialised technology for their laboratory tests.