India trial finds limited effectiveness from convalescent plasma
Using convalescent plasma to treat moderately ill COVID-19 patients did not reduce severity of the illness or risk of death, according to the findings of a clinical trial published last week.
The Indian trial, led by researchers at the Indian Council of Medical Research in New Delhi, found that convalescent plasma did not lead to a reduction in deaths or progression to severe disease by 28 days.
Some countries, including the USA and India, have authorised convalescent plasma for emergency use, while others, such as the UK, are collecting donated plasma so that it can be rolled out if shown to be effective. However, evidence on whether convalescent plasma can prevent deaths from COVID-19 is so far lacking.
The study, published in The BMJ, involved 464 adults, whose average age was 52 and who were admitted to 39 public and private hospitals across India between 22 April and 14 July 2020. All had confirmed moderate COVID-19.
The patients were randomly split into two groups, with 235 patients in the intervention group receiving two transfusions of convalescent plasma, 24 hours apart, alongside best standard of care, while the control group of 229 patients received best standard of care only.
The plasma samples were checked for safety and the levels of neutralising antibodies were also measured. All participants underwent clinical examination and a range of laboratory tests at the start of the trial and again on days one, three, five, seven and 14, and were contacted by telephone on day 28.
After 28 days, 44 (19%) participants in the intervention group and 41 (18%) in the control group had developed severe disease or had died from any cause. However, the treatment did appear to improve shortness of breath and fatigue, and resulted in more people testing negative for SARS‑CoV‑2 RNA after seven days.
The researchers say the study design ensured that the only important difference between the two groups of patients was whether they received convalescent plasma. Restricting the comparison to patients who received plasma with detectable antibody levels did not change the results.
The team acknowledge some limitations, such as differences in the number of patients, laboratory tests, and standards of care across the trial sites that may have affected their results. However, they say the wide social, cultural, and economic mix of study participants mean the findings are likely to be more generalisable.
They conclude that because it showed limited effectiveness, future research could explore using only plasma with high levels of neutralising antibodies, to see if this might be more effective.
Meanwhile, in the UK, a collaboration between two clinical trials currently has more than 1,700 patients due to receive convalescent plasma, making it the largest in the world to test the therapy.
14 additional collection centres have now been opened to increase stocks of convalescent plasma should these trials show it to be effective. NHS Blood and Transplant (NHSBT) has already collected 9,000 units of plasma for the project.
Professor David Roberts, associate medical director for NHSBT, said: “We have so far seen a fantastic response from the public coming forward to donate plasma. We are rapidly building our capability to collect plasma so that we can move into supplying hospitals at scale, should the trial demonstrate patient benefit.”
A UK government minister Lord Bethell said: “The use of convalescent plasma has shown promising results in treating coronavirus and the opening of more donation centres is an important step towards getting this innovative treatment to more patients, if clinical trials demonstrate it should be available on the NHS.”
Agarwal A, Mukherjee A, Kumar G, Chatterjee P, Bhatnagar T, Malhotra P, on behalf of the PLACID Trial Collaborators. (2020) “Convalescent plasma in the management of moderate COVID-19 in adults in India: open label phase II multicentre randomised controlled trial (PLACID Trial).” BMJ, doi: 10.1136/bmj.m3939
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