Transfusing patients with Covid-19 with plasma taken from people who have been infected but have now recovered does not reduce their chance of being seriously ill or dying, according to a study published on Friday, October 23. As a treatment for Covid patients suffering from moderate forms, “Convalescent plasma has shown limited efficacy”, concludes the study carried out in India and published in the medical journal BMJ, which calls, however, to conduct new studies focusing on plasma containing high levels of neutralizing antibodies.
While the range of treatments against the new coronavirus is still very limited and research for a vaccine is continuing, these are the first results of clinical trials intended to assess the benefits of a transfusion of this plasma (liquid part blood which concentrates antibodies after an illness), a method already authorized in some countries such as India or the United States. According to some studies, transfusion of plasma containing antibodies has been shown to be effective in treating Ebola virus or SARS, which is in the same family as the new coronavirus. For Covid-19, recent observational studies have suggested a possible efficacy of plasma.
But in this randomized clinical trial (patients chosen by lot) conducted in dozens of public and private hospitals in India, researchers found that this method failed to reduce mortality or prevent, for moderate patients, progression to a severe case. The study, funded by the Indian Council for Medical Research, enrolled between April and July 464 adult patients, with an average age of 52, and randomly separated them into two groups between April and July.
The control group of 229 patients received usual care, while 235 patients received two transfusions of convalescent plasma in addition to usual care. After twenty-eight days, 44 participants (19%) in the plasma group and 41 (18%) in the control group developed severe disease or died. By limiting the comparison to patients who received plasma with a detectable level of antibodies, the results did not change. In contrast, according to the study, plasma transfusions improved breathing difficulties and fatigue, and the virus was less often detectable after seven days.
This test was “rigorous”, commented public health specialist Elizabeth Pathak in a commentary posted by the BMJ. But Britain’s National Health Service, which conducts the same type of plasma test, was cautious, pointing out that the Indian trial used donated plasma containing between six and ten times less antibodies. than those collected in the UK. “There are other promising elements indicating that convalescent plasma with high levels of antibodies could improve the lot of patients”, he said.