Ashworth has seen bodies laced with blood clots and patients hit with heart attacks, strokes and kidney failure. “I think that in the scientific and political discourse that took place, there was a failure to recognise that we just don’t know very much about this disease,” says Ashworth. “Everybody said, ‘well this is just ARDS and it’s viral’ and actually, what we’ve got is a disease, which if four million people didn’t have it, it would be fascinating. It is fascinating. It’s a fascinating disease. It’s creating avenues for research that will probably help us treat things like flu. It does all sorts of things that we’ve never really thought about before.”

For most people, Covid-19 is mild – a slight fever and dry cough. But for a small number of patients who become critically ill – around six per cent of confirmed cases – Covid 19 warps into a frighteningly lethal condition. In the UK, a third of patients taken to hospital with the disease end up being killed by it.

For the doctors who treat it at this advanced stage, Covid-19 is an enigma. Not only does it damage the lungs in unexpected ways, but it may also invade the heart, gut, blood vessels, kidneys and brain. “We have come back to the virus as the starting point and recognise that it triggers a whole series of different processes,” says Ashworth. HIV is the archetype of a complex disease, he says. “Covid-19 is not far off it.”