Convalescent plasma, the liquid part of the blood that concentrates antibodies after illness, has already proven to be effective in small-scale studies against other infectious diseases like Ebola or Sras.

The US drug agency, the Food and Drug Administration (FDA), has given the green light to test such treatments against the coronavirus, which has already infected more than 245,000 people in the United States. The total number of people who have died since the start of the pandemic in the country is now around 6,000.

In France, a clinical trial, supported by the French Blood Establishment, must begin next week, according to France Inter.

However, current experiments are not intended to lead to a miracle solution against Covid-19, says Bruce Sachias, medical manager of the New York Blood Collection Center, responsible for collecting, testing and distributing plasma donations in the main American metropolis. "We must be aware of the fact that we are still in unknown territory," he told AFP.

Each donation could "potentially save three or four lives"

Eldad Hod and Steven Spitalnik, the transfusion specialists who run these experiments at Columbia University's Irving Hospital, also point to the extent of the uncertainty. It is believed that "within seven to 14 days after the start of an infection, people develop an immune response and end up producing large quantities of antibodies. But it is not known exactly when the manufacturing peak occurs", explains Doctor Spitalnik.

There is some data to suggest that the spike occurs about 28 days after infection, and he hopes their research will provide a more accurate picture. Each plasma donation could "potentially save three or four lives," says Dr. Hod.

The goal now is to collect enough plasma for researchers to conduct formal studies with groups of control patients who will receive non-convalescent plasma.

The first plasmas will nonetheless be intended, "out of compassion", for patients not included in the study, but for whom the other treatments have failed, confides Mr. Hod.

The researchers would then like to test the method on patients already hospitalized, and as a preventive treatment in vulnerable environments, such as residences for the elderly.

Normally, they would conduct very controlled and lengthy clinical trials, but with more conclusive results. But "we are in crisis," says Spitalnik.

"Science will prevail"

Having recovered from her forties, Diana Berrent, a 45-year-old New York photographer, launched a group on Facebook, the "Survivor Corps", already 17,000 strong, to mobilize survivors of the epidemic ready to share their immunity .

Hundreds of recovered people have already offered help in New York, the epicenter of the epidemic in the United States with nearly 100,000 cases, according to Dr. Sachias.

If the process is successful, similar plasma collection systems will be put in place at other blood centers, he says.

A Houston, Texas hospital has previously tried to transfuse plasma from a cured patient to another critically ill patient, but it is too soon to know its effectiveness.

As studies begin, Eldad Hod believes that one of the positive aspects of the pandemic is that it has stimulated collaboration between researchers around the world, who have never shared their data so openly.

"Many in the scientific community try to put their ego aside (...) and work together for the common good. I think in the end, science will prevail."

With AFP

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