A new effort is under way to understand how the immune system responds to coronavirus.
Scientists from 17 UK research centres are attempting to answer questions such as how long immunity lasts and why disease severity varies so much.
The new UK Coronavirus Immunology Consortium (UK-CIC) says learning about immunity will help to fight the virus.
It has received £6.5m from UK Research and Innovation (UKRI) and the National Institute for Health Research (NIHR).
Prof Mala Maini, a viral immunologist from University College London, who is leading one of the UK-CIC teams, said: “Our immune response to a virus is really what dictates how we respond when we get infected, how ill we get when we get an acute infection, how long we're protected after we've had the infection and how well we might respond to a vaccine.
“The immune system is underlying everything that's key to the response to this virus.”
Since the virus first emerged, scientists have been racing to learn about how our bodies respond to infection.
Prof Maini says for mild-to-moderate cases of Covid-19 the immune response seems to be “textbook”.
She explained: “All the right components of that complex immune system seem to be working together well.”
More severe cases
But the consortium is hoping to find out the role the immune system plays in more severe cases.
It is also seeking answers to how long immunity lasts. This week, researchers in Hong Kong reported the first documented case of re-infection.
Prof Paul Moss, UK-CIC principal investigator from the University of Birmingham, said: “It’s the first case out of millions, so we have to keep it in proportion.”
He said it was a concern that the immune response to coronavirus seemed to wane over time.
But he said the fact that the man had no symptoms during his second infection suggested the immune system could be effective at halting the disease.
The consortium will also be studying whether some people have pre-existing immunity to the virus, even though they have never been exposed to it.
Several studies have shown that an earlier encounter with some of the coronaviruses that cause the common cold enables the immune system to recognise the new coronavirus.
Prof Moss said a key question was to find out whether infection with other mild coronaviruses could protect you from catching Covid-19 or make you more ill.