A new study from India says convalescent plasma did not reduce deaths among Covid-19 patients or prevent moderate disease from becoming severe.
Plasma taken from the blood of recovered Covid-19 patients that is given to people sick with the disease does not reduce their chances of getting seriously ill or dying, it said.
The study was conducted in India and published in the medical journal the BMJ on Thursday, reports CNN.
The findings suggested that "as a potential treatment for patients with moderate Covid-19, convalescent plasma showed limited effectiveness."
The research, which involved more than 400 people who were in hospital with COVID-19, investigated convalescent plasma as a treatment for people with moderate disease, reports AJ Jazeera.
The findings of one of the first clinical trials to investigate the efficacy of convalescent plasma are a setback for a treatment that US President Donald Trump touted in August as an “historic breakthrough”.
The US and India, battling the world’s worst outbreaks of Covid-19, have both authorised convalescent plasma for emergency use.
Other countries, including the United Kingdom, have been collecting donated plasma so that it could be widely rolled out if shown to be an effective treatment.
“The … trial was able to show a small effect on the rate at which patients were able rid themselves of the virus, but this was not enough to improve their recovery from the disease,” said Simon Clarke, an expert in cellular microbiology at the University of Reading.
“In simple terms, there were no clinical benefits to the patients.”
With no cure or vaccine, countries have been scrambling to find ways to moderate the effect of the virus.
The convalescent plasma technique was first tried against diphtheria in 1892 and was shown to help speed recovery from Ebola and SARS, which is caused by the same family of pathogens as the novel coronavirus.
The new study, funded by the Indian Council of Medical Research, enrolled 464 adult patients, with an average age of 52, between April and July and split them randomly into two groups.
A control group of 229 was given the normal best standard of hospital care, while 235 people received two transfusions of convalescent plasma and the best standard of hospital care.
After seven days, use of convalescent plasma seemed to improve some symptoms, such as shortness of breath and fatigue, the researchers said, and led to higher rates of something known as “negative conversion” – a sign that the virus is being neutralised by antibodies.
But this did not translate into a reduction in deaths or progression to severe disease by 28 days.
After that period, 44 (19 percent) of the participants in the plasma group and 41 (18 percent) in the control group progressed to severe disease or died from any cause.
When they restricted the comparison to patients who received plasma with detectable levels of antibodies, the results were the same, the authors said.
The trial “was a rigorous randomised controlled study on a topic of enormous global importance” said public health scientist Elizabeth Pathak in a separate commentary also published in the BMJ.
The researchers said future studies could explore using only plasma with high levels of neutralising antibodies to see if this might be more effective.
The results were greeted with caution by a spokesman from the United Kingdom’s National Health Service, which is also in the process of carrying out large, randomised control trials of convalescent plasma.
The official from the NHS blood and transplant department said that the Indian trial had used donations with antibody levels around six to 10 times lower than in the UK.
He said there is “other promising evidence” that convalescent plasma transfusions with high antibody levels could improve patient outcomes.
The point at which a patient receives the plasma might also be important, according to some researchers.
Ian Jones, a professor of virology, also at Reading University, says the plasma is more likely to work if given very soon after someone contracts Covid-19.
He urged these and other researchers to continue to conduct trials of convalescent plasma in newly diagnosed patients.