Study of blood plasma as Ebola treatment yields disappointing results

Blood transfusions drawn randomly from survivors of Ebola may offer little benefit to people afflicted by the disease, according to a report today in The New England Journal of Medicine. Just 69 percent of 84 Ebola patients survived after receiving a transfusion of a survivor’s plasma (blood minus the blood cells). That was only slightly higher than the 62 percent of patients who survived without receiving the plasma.

Doctors in West Africa launched the study last winter as deaths mounted from the most recent Ebola outbreak. During a small flare-up in the Democratic Republic of Congo in 1995, seven out of eight Ebola patients infused with survivor blood lived, sparking hopes that blood transfusions could offer a cure for the highly dangerous illness. Unlike experimental drugs, survivor blood is cheap and plentiful during outbreaks. A team of clinician scientists from countries in Europe and Africa conducted the study at a Doctors Without Borders clinic in Conakry, Guinea, with guidance from the World Health Organization.    

Although the results were disappointing, researchers say that survivor blood deserves additional testing because they randomly chose blood donations and didn’t determine which donations contained high levels of blood’s key ingredient against Ebola, antibodies that glom onto the virus and block it from causing harm. It can take weeks for a person’s immune system to produce these antibodies, and some people naturally produce more than others. Johan van Griensven, the lead author on the report and an infectious disease specialist at the Institute of Tropical Medicine in Belgium, says the plasma might have worked better if the researchers used only samples containing high concentrations of antibodies.

That didn’t happen, in part because laboratories in Guinea lacked the technology to safely test survivor blood donations for antibody levels. But the researchers are now sending samples of the donated blood to France, where they can test antibody levels as well as data on how patients’ viral levels changed after the infusion. Those results will be available in a few months, van Griensven said.

“This could go in two directions. One is that survival and changes in viral load correlate with the amount of antibody present, which will provide strong evidence of a causal link,” he said. “That would mean we should stockpile plasma.” The other possibility is that the follow-up will find no correlation, which means transfusing survivor blood is not a cure.

The trial was funded by a $3.1 million grant from the European Union, with additional support from the Bill and Melinda Gates Foundation. A far less expensive study led by Sierra Leonean scientists on whole blood (which includes red cells) showed preliminary signs of success — reported previously in Al Jazeera America — but those data have yet to be peer-reviewed and published in a scientific journal.

On Dec. 29, Guinea was declared Ebola-free. The outbreak killed 8,414 people in West Africa; an additional 13,000 people were infected and survived.

A virologist who was not involved with the study, Daniel Bausch of Tulane University, called today’s results “sort of preliminary.” Before studying Ebola, he focused on Lassa fever, another viral disease that causes bleeding. Data suggest that survivor plasma can help stem Lassa, he said, but only if the blood has high antibody levels. Until the antibody levels of the Ebola survivors’ plasma are known, Bausch said, “we should not just toss this idea out into the trash.”