Covid patients should not be given the blood of survivors because it does not help them fight off the virus, the World Health Organization said today.
Medics had hoped that convalescent plasma — a straw-coloured fluid in the blood that contains antibodies — could help the infected recover.
But a slew of studies have shown that the treatment, used for over a century to treat infections, does not boost survival rates.
The WHO’s guideline development group made the recommendations in today’s British Medical Journal.
It said: ‘Despite its initial promise, current evidence shows that [the treatment] does not improve survival nor reduce the need for mechanical ventilation.’
The NHS stopped using the plasma in January after world-leading British trials found ‘no convincing evidence’ that it helped patients.
Only 5,700 hospitalised Covid patients were administered blood plasma in the UK following a national recruitment drive for survivors to donate.
It is not clear which nations are still using the treatment. The US stopped using the therapy in March.
Medics had hoped that convalescent plasma — a straw-coloured fluid in the blood that contains antibodies — could help patients recover from an infection. Pictured: A woman donating blood plasma in Seattle after surviving Covid
Blood plasma therapy works by harvesting antibodies from survivors.
If someone’s donating plasma, their blood is drawn through a tube and the fluid is separated from the blood. The rest is infused back into the body.
Then the plasma is tested and purified to be sure it does not harbour any blood-borne viruses and is safe to use.
The treatment was previously used during the Spanish flu outbreak in 1918, and more recently to treat H1N1 in 2009 to 2010 and MERS in 2012.
Writing in the BMJ, the WHO group strongly recommended against administering the plasma to non-severe patients, and recommended against its use in those who were severely unwell.
Citing data from 16 trials, the panel said it ‘does not improve survival’ nor ‘remove the need for mechanical ventilation’.
Officials also branded the treatment costly and time-consuming to prepare and administer to unwell patients.
Sources said that although the UK had stopped using the treatment, the guidance was likely for third-world countries.
It follows on from results published by Oxford University’s landmark RECOVERY trial in January — which led to the treatment being suspended in the UK.
Researchers followed 5,795 hospitalised Covid patients given normal treatment and blood plasma, and a similar-sized group not given the therapy.
Results showed there was no difference in the proportion that died from the virus (24 per cent in each group).
There was also no difference in the proportion discharged within 28 days of admission (66 per cent in blood plasma group against 67 per cent in those receiving normal treatment).
The study found no evidence that any patients who received the treatment were harmed.
Scientists said at the time that although the results were ‘negative’, the trial had only been made possible ‘thanks to the generous donation of plasma by recovered patients’.
Experts said the treatment may not work in severely ill patients because so much damage had already been done to their lungs by an infection.
The timing of administering the plasma, and an insufficient dose were also suggested as possible factors behind why it failed.
Sources said the treatment differed from monoclonal antibody therapies because these contain far higher antibody concentrations.
Monoclonal antibodies are manufactured in laboratories and work by mounting an immune response against the virus in people whose bodies are too weak to do it on their own.
NHS Blood and Transplant — which manages blood plasma donations — is still collecting the fluid to develop antibody treatments for those with compromised immune systems such as long term cancer patients.
An NHSBT spokesman said: ‘This guideline recommending against the use convalescent plasma outside of trials was developed in part thanks to the world leading research supported by NHSBT.
‘While these trials have shown unselected patients do not benefit from convalescent plasma, further research is needed into whether convalescent plasma may benefit some specific, vulnerable patient groups.’
WHAT IS CONVALESCENT PLASMA AND WHERE HAS IT BEEN USED?
Convalescent plasma has been used to treat infections for at least a century, dating back to the 1918 Spanish flu pandemic.
It was also trialed during the 2009-2010 H1N1 influenza virus pandemic, 2003 SARS epidemic, and the 2012 MERS epidemic.
Convalescent plasma was used as a last resort to improve the survival rate of patients with SARS whose condition continued to deteriorate.
It has been proven ‘effective and life-saving’ against other infections, such as rabies and diphtheria, said Dr Mike Ryan, of the World Health Organization.
‘It is a very important area to pursue,’ Dr Ryan said.
What is blood plasma?
Blood plasma is a straw-coloured fluid that carries red and white blood cells and platelets (which trigger blood clots) around the body.
It also contains antibodies to fight off viruses, including Covid in those who have recovered from an infection.
Medics had hoped that the antibodies in the plasma would help Covid patients to recover from the disease.
How does it work?
Blood banks take plasma donations much like they take donations of whole blood; regular plasma is used in hospitals and emergency rooms every day.
If someone’s donating only plasma, their blood is drawn through a tube, the plasma is separated and the rest infused back into the donor’s body.
Then that plasma is tested and purified to be sure it doesn’t harbor any blood-borne viruses and is safe to use.
For Covid research, people who have recovered from the virus would be donating.
Scientists would measure how many antibodies are in a unit of donated plasma — tests just now being developed that aren’t available to the general public — as they figure out what’s a good dose, and how often a survivor could donate.
There is also the possibility that asymptomatic patients — those who never showed symptoms or became unwell — would be able to donate. But these ‘silent carriers’ would need to be found via testing first.
Japanese pharmaceutical company Takeda is working on a drug that contains recovered patients antibodies in a pill form, Stat News reported.