Convalescent plasma therapy for severe SARS-CoV-2
August 8, 2020 - South African researchers have started a study to see whether the plasma from donors who’ve had the coronavirus and developed antibodies can help those who are severely ill with Covid-19.
“The hope is that antibodies in plasma will shorten and lessen the illness,” Karin van den Berg of the South African National Blood Service (SANBS), said.
The SANBS has started collecting plasma from donors and is waiting for the Human Research Ethics Committee’s approval before it can begin a randomized clinical trial on 600 patients. Half of these will get plasma and the other half a placebo.
Convalescent plasma has successfully reduced the death rate of hospitalized patients, according to America’s Johns Hopkins Bloomberg School of Medicine in Baltimore, Maryland. Britain’s Guy’s and St Thomas’ hospital in London and Greece’s Attiko and Evangelismos hospital in Athens are also running trials.
India’s three states with the highest number of Covid-19 cases -- Maharashtra, Tamil Nadu and Delhi -- have sought permission from the Council of Medical Research to conduct convalescent plasma therapy tests. The SANBS trial is the first in Africa.
Plasma is the cell-free liquid part of blood after the removal of all red and white blood cells and platelets. Plasma from the blood of a recovered Covid-19 patient is rich in antibodies -- proteins secreted by immune cells called B lymphocytes, or B cells, to target a pathogen such as SARS-Cov-2 for destruction.
One cured person’s plasma can produce two doses of the transfusion material. Critically ill patients receive 200-400ml of plasma intravenously, and their progress is then carefully monitored.
While vaccination provides life-long immunity, in the case of passive antibody therapy, the effect lasts only so long as the injected antibodies remain in the blood.
The therapy was first used over a century ago in 1918 during the Spanish flu pandemic. The most recent instances include the 2018 Ebola outbreak, the H1N1 epidemic of 2008-2009, on SARS which broke out in 2003 and MERS in 2012.
Graphic News Standards