COVID-19 convalescent plasma therapy trial to begin in South Africa
University of Cape Town’s (UCT) Prof Sean Wasserman is leading plasma therapy trial in South Africa in partnership with the South African National Blood Service. There has been a lot of buzz around plasma-derived therapy for the treatment of COVID-19, especially since US President Donald Trump announced emergency authorisation for it to take place. The basic explanation for the process is that blood is taken from recovered COVID-19 patients who have built antibodies against the virus, the blood plasma is separated and transfused into people with COVID-19. It is believed to be most effective when given to patients within their first three days of hospitalisation. But is it a therapeutic treatment that has merit? The process involves taking blood plasma from recovered COVID-19 patients and infusing it into those still recovering from the illness. Wasserman is leading one of those trials in South Africa, in partnership with the South African National Blood Service, which is due to begin within weeks. Plasma is the constituent of blood that gets separated out from the other components of blood such as cells and platelets for therapeutic purposes, explains Wasserman. “Plasma contains mainly proteins and specifically for this indication, it contains antibodies, which are proteins and important in neutralising antibodies, which are thought to have the potential to neutralise viruses”, said Prof Wasserman.
“Convalescent plasma has been used for about 150 years and is plasma donated from people who have recovered from viral infections. In this case, it would be plasma from those who have recovered from COVID-19. Most of the evidence comes from influenza but also other coronaviruses, including the related SARS, which was an epidemic in the early 2000s”, he added.
However, he says there have not been large randomised controlled trials which remains the highest-quality evidence of evaluating the efficacy of convalescent plasma for these infections including COVID-19. “But large observational studies have been done...which do show promise”, he said. These observational studies show convalescent plasma has multiple beneficial effects. It results in clinical improvement and also lower mortality benefits so there is definitely promise. It is used routinely in medical treatment with very rare adverse events.
If there are very few adverse effects, even if it has not yet gone through the randomised double-blind placebo-control (RDBPC) studies, which are considered the gold standard of epidemiologic studies, should it not be used more widely for treating COVID-19 as a 'just in case', asks John Maytham?
Wasserman replies that this goes to a broader debate around evidence-based medicine in an epidemic. “The more something is used, then the more information comes out and potentially harmful events that aren't detected in uncontrolled trials can emerge. Without the gold standard trials, other factors may enter the equation he explains, such as plasma being given to someone who would have recovered anyway. And while plasma treatment's adverse effects are not high, they are also not zero”, replied Prof Wasserman.
“Some of the adverse effects associated with convalescent plasma are potentially fatal. High quality randomised controlled trials are needed before this is something that can be widely used”, he concluded.
The risks of transmitting other blood-borne viruses through plasma therapy, such as HIV or hepatitis, are the same as for any other blood transfusion, says Wasserman.
Convalescent plasma is a blood transfusion. All blood services world-wide have very strict procedures for screening donors and transmission rates for other viruses are very low. Other plasma treatment risks are allergic reactions, direct lung injuries and fluid overload, which are very rare.
When asked whether there are high-quality double-blind randomised control trials for plasma therapy underway in South Africa? he responded, “I am leading one of those trials in South Africa, in partnership with the South African National Blood Service. The trial will begin within the next few weeks with about 600 participants who will either receive plasma or the placebo, he added.
Source: Cape Talk