Convalescent plasma as a possible Covid-19 therapy

22 Jul 2020

A trial is underway to investigate the effectiveness and safety of treating patients with moderate to severe Covid-19 pneumonia with convalescent plasma (CP) from people who have recovered from the virus. Investigators at the University of Cape Town (UCT) are working with the South African National Blood Service (SANBS) and the Western Cape Blood Service (WCBS) to conduct the Protect-patient trial.

SANBS CEO, Dr Jonathan Louw, was among one of the first people diagnosed with Covid-19 in South Africa. He is giving back by making the country’s first convalescent plasma donation.

The trial comes as a surge of Covid-19 infections is projected to peak in the country between July and September 2020. The spike of infections, according to South Africa’s health minister Dr Zweli Mkhize, has changed hands from the Western Cape to Gauteng now becoming the epicentre of the pandemic.

“Other safe, accessible, and affordable treatment options are clearly needed and must be established through the conduct of well-designed clinical trials before being used in routine patient care," said Associate Professor Sean Wasserman at the Department of Medicine in the Faculty of Health Sciences, and the co-principal investigator of the Protect-patient trial.

International experience, which has been mirrored in South Africa, has shown that around a quarter of the people who need oxygen for more severe Covid-19 pneumonia may die from the disease.

“Outcomes for those placed on ventilators for respiratory failure is worse. Various drugs are being investigated to reduce the need for mechanical ventilation and improve survival for those with severe Covid-19; two have shown some efficacy so far, only one of which (dexamethasone) is available in South Africa,” he said

Hypothesis

It is hypothesised that infusing plasma that has virus-specific antibodies will provide immediate transfer of passive immunity to the recipient and may improve their clinical course and outcomes by accelerating viral clearance and antibody-dependent killing of infected cells.

“The use of CP as passive immunisation to treat viral infections is not novel. Early administration of CP has proved successful in reducing mortality from severe influenza as well as the related epidemic coronavirus severe acute respiratory syndrome (SARS)-CoV and has been used successfully in Middle East respiratory syndrome (MERS)-CoV and Ebola virus disease," Wasserman said in a paper he co-authored and published in The South African Medical Journal.

“Where CP was used to treat SARS-CoV infections, the absolute risk reduction in mortality ranged between 7% and 23%, and CP was associated with earlier discharge from hospital. It is because of the positive results of these trials, in addition to the lack of successful treatment options available at present, that the use of CCP has been considered in the current SARS-CoV-2 pandemic.”