Britain is to start trials to see whether plasma collected from donors who have recovered from COVID-19 could be an effective treatment for patients who are severely unwell with the disease.

Up to 5,000 severely ill patients with COVID-19 could soon be treated each week with plasma as part of a new approach to treating the virus, the health department said on Saturday.

Plasma from recovered COVID-19 patients can be transfused to patients who are struggling to produce their own antibodies against the virus.

So-called convalescent plasma was used as an effective treatment during the 2002 to 2004 SARS outbreak, the health department said.

In parallel with the national randomized clinical trial, the government is scaling up the national program for collecting plasma so the treatment can be widely rolled out if it is shown to be effective, the department said.

The collection of plasma would be ramped up over April and May to deliver up to 10,000 units of plasma to the National Health Service (NHS) every week, enough to treat 5,000 COVID-19 patients per week.

“I have every hope this treatment will be a major milestone in our fight against this disease,” said health minister Matt Hancock.

Professor Jonathan Van-Tam, Deputy Chief Medical Officer said: “The UK is leading the world’s largest trials to find a treatment for COVID-19, with over 7,000 people so far involved testing a range of medicines; we hope to add convalescent plasma to this list shortly.”

He added: “Convalescent plasma has been used as an effective treatment for emerging infections in the past, and this step forward underpins our science-backed approach to fighting this virus.”

The NHS will contact people in England who have recovered from COVID-19 and could be possible donors.

Blood is taken from one arm and circulated through a machine that separates out the plasma, and then returned to the donor. The process takes about 45 minutes and provides two units of plasma per donation, which can also be frozen and stored ahead for any future need.