Giving hospitalised Covid patients blood plasma transfusions from virus survivors may cut their risk of dying after all, scientists now say.
Medics had hoped infusions of convalescent plasma — a straw-coloured fluid in the blood that contains antibodies — could help the infected recover.
But a series of studies showed the treatment does not boost survival rates, leading to the World Health Organization to recommend it only be used for severely unwell patients.
Now, researchers in New York have found those treated with the therapy were 15 per cent less likely to die within four weeks.
Patients at most risk from the coronavirus, such as those battling diabetes or heart disease, benefitted even more from the treatment, the team said.
The experts examined the results of eight existing studies, which involved more than 2,000 Covid patients.
They argued that older trials were too small to notice the effect of the treatment, which has been used to treat infections for at least a century.
Professor Andrea Troxel, study leader and a biostatistician at NYU Langone Health, said: ‘Our results show, overall, patients hospitalised with Covid may derive modest benefit from convalescent plasma.
‘Patients with co-existing disease were most likely to show improvement from convalescent plasma, probably because they have the most difficulty producing antibodies to fight their infection.
‘The infused plasma boosts their body’s ability to fight the virus, but only in the early stage of the disease and before the illness overwhelms their body.’
In the UK, trials of convalescent plasma as a Covid treatment were suspended after scientists said results did not show the therapy helped moderately ill people.
But the treatment is given to hospitalised patients in the US who have suppressed immune systems.
Convalescent plasma (pictured) — the main component of blood that contains antibodies and other immune cells needed to fight the infection — taken from Covid survivors may cut the risk of patients dying, NYU researchers said
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.
NYU researchers examined data from eight different studies — completed in the US, Belgium, Brazil, India, Spain and the Netherlands — to assess how effective the treatment was.
The studies included 2,341 people hospitalised with Covid, who were aged 60 on average and were given an injection of blood plasma.
Plasma is the biggest component in blood, making up 55 per cent of it, and contains antibodies.
The team found that those given the treatment soon after being hospitalised were 15 per cent less likely to die within a month, compared to those who did not receive it or were given a placebo transfusion.
The study, published JAMA Network Open, contradicts earlier findings that the therapy is ineffective or of limited value.
Imperial College London last year halted their trial of the treatment after data on nearly 1,000 patients showed ‘no evidence’ convalescent plasma boosted survival rates.
And Oxford University researchers last year followed suit after an analysis of 1,800 deaths among 10,400 patients showed it made ‘no significant difference’.
Subsequently, the WHO advised doctors to restrict the treatment to only severe and critical patients as part of clinical trials.
The agency, which examined 16 trials including more than 16,000 patients, concluded the treatment does not improve survival rates or reduce the risk that a patient will need a ventilator. It is also expensive and time-consuming to administer.
However, it said critically ill patients may benefit from it, so clinical trials of the treatment should continue.
But Professor Troxel said pooling results from multiple studies shows the benefits of the treatment, as the others were too small to show its impact on subsets of patients.
Study investigator Dr Mila Ortigoza said convalescent plasma collected from previously infected and subsequently vaccinated donors would contain high levels of antibodies that could protect against future mutations of the virus.
So convalescent plasma may offer faster and more robust treatment against Covid’s variants than other therapies that ‘tend to become less effective with time and must undergo a redesign process to address a new variant, such as monoclonal antibody treatments’, she said.
Study co-investigator Professor Eve Petkova, a population health expert at the university, said the team is using the findings to create a scoring system to make it easier for medics to calculate who benefits most from the treatment.