Limited efficacy of plasma from cured patients, study finds

Grant Boone
October 27, 2020

But Canadian researchers continue to study its potential. But because people's immune systems vary widely, their volume of disease-fighting cells is also unpredictable, and may range from barely adequate levels to extremely rich sources of immune cells.

Researchers yesterday called for more study on using blood from recovered Covid-19 patients - or so-called convalescent plasma - as a potential treatment, after a small trial of hospitalised patients in India found no benefit.

Randomized controlled trials of convalescent plasma to treat Covid-19 patients are still underway in the United States.

Patients were randomised to either CP and best standard of care (intervention group) or care lone (the control group) and intervention patients received two doses of 200ml CP transfused 24 hours apart.

The Indian researchers enrolled 464 adults with Covid-19 who were admitted to hospitals across the country between April and July.

They did however find that the use of convalescent plasma seemed to improve resolution of shortness of breath and fatigue and led to higher conversion to a negative result for the virus - a sign of it being neutralised by antibodies - after 7 days.

Weekly US COVID-19 deaths up 15%, new cases rise 24%
As with the MI data, the state numbers are updated daily but can lag behind local reports or have other discrepancies. The state also reported that new antibody tests had been completed for 144 people, bringing that total to 125,973.

Two other worldwide studies also failed to find a benefit of convalescent plasma, but those were stopped early because too few eligible patients were enrolled. Additionally, more research is needed to determine whether similar findings would emerge among a larger group of patients in other parts of the world.

The way FDA commissioner Stephen Hahn characterized the benefits of convalescent plasma for COVID-19 patients raises concerns about political interference, says Dr. Samir Gupta, an associate professor in the Department of Medicine at the University of Toronto.

'The trial was able to show a small effect on the rate at which patients were able rid themselves of the virus, but this was not enough to improve their recovery from the disease, ' said Simon Clarke, an expert cellular microbiologist at the University of Reading. Health officials said recovered means the patient is not hospitalized or deceased and it has been 14 days since the onset of symptoms or report. She noted that COVID-19 is "a life threatening thrombotic disorder", meaning it causes blood to thicken and clot, and the primary goal of giving people plasma infusions is to treat acute bleeding and bleeding disorders - conditions in which it would be good if blood thickened.

By limiting the comparison to patients who received plasma with a detectable level of antibodies, the results did not change. Key public health leaders including Dr. Francis Collins, director of the National Institutes of Health, and Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, however, have noted that researchers are still studying convalescent plasma's role in COVID-19.

But ICMR has made it clear that even for the purposes of trial, it can be used only on critical patients who are on ventilator support.

"For example, one could well imagine that the treatment might work particularly well in those earlier in the course of the disease or who have not been able to mount a good antibody response to the virus of their own", Landray said. "But such speculation needs to be tested".

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