Convalescent plasma does not help severely ill Covid patients – trial
Convalescent plasma from people who have had Covid-19 does not help those who are severely ill in intensive care to recover, a major international trial has found.
No more very sick people will be recruited to the trial, known as RemapCap. But NHS Blood and Transplant (NHSBT) has urged people who have recovered from Covid to keep donating blood. Nobody yet knows whether convalescent plasma could help people who are moderately ill, they say. Those trials continue and and if plasma works it would be available in every country in the world.
The pausing of the trial is not linked to recent speculation that the use of convalescent plasma could be one of the reasons for the emergence of the variant known as B117 in Kent last year. A paper found a mutation in the virus that caused the death of a patient whose immune system was severely compromised and who had received convalescent plasma.
“It is possible that the mutations arose and were selected in one or more people who had long-lasting infections and poor immune responses,” said Prof Dave Roberts, associate medical director at NHSBT.
“But there is no evidence the new B117 variant evolved in somebody treated with convalescent plasma. The authors of the paper acknowledge their hypothesis is a ‘speculation’.”
The Remap-Cap trial is investigating new therapies for Covid-19 in more than 4,000 patients in 290 clinical sites around the world. Recently it reported a success – that the arthritis drugs tocilizumab and sarilumab could potentially cut the relative risk of death among people in intensive care with Covid by 24%.
But the trial’s independent oversight board has now reported that convalescent plasma is unlikely to help those who are in intensive care, based on an analysis of data from 912 patients who were severely ill. However, it is important to find out whether there are still people who can benefit.
“It is biologically plausible that patients who are not producing antibodies at the time of convalescent plasma therapy and those patients with excess virus may benefit more than others,” said Dr Manu Shankar-Hari, professor of critical care medicine at Guy’s and St Thomas’ NHS Foundation trust in London.
“Our additional analyses will explore this. Aside from these severe patients, patients who are moderately ill and patients with immune impairments may benefit.
“It is therefore vital that plasma donations continue.”
Dr Peter Horby, professor of emerging infectious diseases at Oxford University and chief investigator for the Recovery trial which is still using convalescent plasma, urged people to continue to donate. “We don’t yet know if convalescent plasma works as a treatment for Covid patients, but if it does it would have a major impact worldwide,” he said.
“Plasma from patients who have recovered from Covid-19 contains antibodies that may help to speed up clearance of the virus from those who are suffering from the disease and improve their chances of recovery, particularly if they are treated before they become severely ill.