New York, June 19 : Researchers in the US have found that Covid-19 patients who received transfusions of blood plasma from people who recovered found the treatment was safe. The study of 20,000 hospitalised patients with Covid-19, published in the Mayo Clinic Proceedings, suggests that giving blood plasma to people early in the disease may be beneficial. "Our efforts to understand convalescent plasma continue. We're optimistic but must remain objective as we assess increasing amounts of data," said study lead author Michael Joyner from the Mayo Clinic in the US. The safety report assessed the seven days following transfusion for hospitalised patients between April 3 and June 11 who were deemed at risk of progressing to a severe or life-threatening condition. The findings showed that Seven-day mortality rates declined to 8.6 per cent compared to 12 per cent in a previous safety study of the first 5,000 transfused patients. Serious adverse events continued to be less than one per cent. This expanded safety report reveals a decline in mortality which appears contemporary with the more rapid availability of plasma for use, but the authors caution that this alone does not provide any evidence on the effectiveness of convalescent plasma for treating Covid-19. Given the accelerating use of the therapy, research is now broadening its focus to determine indicators of efficacy. At this time, convalescent plasma therapy is the only antibody-based therapy for Covid-19.The researchers said that while the mortality rate has decreased, the patients in the latter part of this study were less critically ill. They also said the decrease may be in part due to improved medical care based on increased knowledge during the pandemic and that more of the patients received the plasma earlier in their hospital treatment. The research team noted that there was no system in place for delivering convalescent plasma in March and now there is sufficient donation to meet most of the demand.Also, as donors came forward more rapidly, it was more likely their plasma contained neutralising antibodies, they wrote. As of Friday morning, the overall number of global Covid-19 cases has topped to over 8.4 million, while the deaths have surged to more than 453,000. With 2,189,128 cases and 118,421 deaths, the US continues with the world's highest number of Covid-19 infections and fatalities, according to the Johns Hopkins University. /IANS