Positive signs from plasma treatment tests on 20,000 COVID-19 patients

Researchers in the US have observed reduced mortality in COVID-19 patients who were given convalescent plasma with anti-viral antibodies, prompting calls to shift the focus of studies from safety to efficacy.

Mayo Clinic scientists and collaborators have found investigational convalescent plasma to be safe following transfusion in a diverse group of 20,000 patients with the disease.

The safety report assessed the seven days following transfusion for hospitalized patients between 3 April and 11 June who were deemed at risk of progressing to a severe or life-threatening condition.

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 percent.

"Our efforts to understand convalescent plasma continue," says Michael Joyne,r MD, principal investigator of the EAP at Mayo Clinic and lead author of the article.

"We're optimistic but must remain objective as we assess increasing amounts of data."

The 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 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.

The 7000-plus physicians who are part of the program have done an exceptional job of offering convalescent plasma to a diverse group of patients, enrolling women as forty percent of the participants as well as significant numbers of patients who are of African American, Asian or Hispanic ethnicity," says researcher DeLisa Fairweather, PhD.

"We hope recruitment of minority subjects continues to increase given the disproportionate burden these communities have faced with COVID-19," Fairweather says.

The researchers say that while the mortality rate has decreased, the patients in the latter part of this study were less critically ill.

They also say 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.

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There are now close to 9.19 million COVID-19 cases worldwide with 474,258 deaths recorded.

Nearly 2.4 million of these cases are in the US where the death tally stands at 122,610, which is more deaths than the country recorded in World War I.

Case rates are rising rapidly globally, particularly in Brazil and India where the numbers of new daily cases continue to skyrocket.

Chile and Peru, whose combined population of around 51 million is dwarfed by other virus hotspots, have also seen a worrying increase in infection rates. If counted together, these two Andean countries would constitute the fourth hardest-hit region behind the US, Brazil and Russia. 

Updated at 11:36am AEST on 23 June 2020.