More than 6,500 people have signed up for a trial to see if blood plasma from Covid-19 survivors can treat hospital patients who are ill with the virus.
It is hoped transfusing seriously ill patients with so-called convalescent blood plasma will give their struggling immune systems a helping hand.
The plasma, the liquid portion of the blood, contains coronavirus antibodies.
Antibodies are proteins made by the immune system which can target the virus and neutralise it.
They build up over about a month after contracting Covid-19.
Last week, NHS Blood and Transplant began collecting blood from survivors. So far in England 148 people have donated their plasma.
Researchers are looking through NHS data to find other people who have tested positive for coronavirus, who will then be asked if they wish to be involved in the trial.
Donating takes about 45 minutes, as the blood is filtered through a machine to remove the plasma. The process is technically known as plasmapheresis.
Dr Manu Shankar-Hari, a joint lead on the trial that will involve hospitals around the UK, said people currently do not have protection in their immune systems because Coronavirus is new.
"What we are doing with this trial is to give you instantaneous protection against the virus using an antibody that is developed by patients who recover from the virus,
"So the hope is that the viral clearance or the taking away of the virus in the body will be quicker by giving this treatment."
'Terrified of needles'
At a special plasma donation session in Birmingham this week, donors were enthusiastic about the chance to help those currently hospitalised with the disease.
Jo Toozs-Hobson said she decided to take part despite being terrified of needles after her whole family got sick - her husband was in hospital for five days.
"I wouldn't normally give blood but something came up on Facebook about this and I thought, I've got to do this because of the experience we went through," she said.
NHS Blood and Transplant is also preparing to collect and deliver plasma in large quantities if transfusions are shown to help patients.
It aims to collect up to 10,000 units a week by early June.
Similar trials are already under way around the world.
The University Hospital of Wales in Cardiff hopes to offer the treatment as part of a study.
The US has already started a major project involving 2,000 hospitals and has treated about 4,400 patients.