Study sheds light on Ebola transfusions

At the height of the Ebola epidemic, one of the most promising — if unproven — therapies was blood transfusions from people who had survived the deadly virus. Their blood plasma was presumed to have Ebola antibodies that could go to work right away. And there was evidence that survivor blood helped patients recover from other infectious diseases like influenza and SARS.

With patients dying daily, some doctors went ahead and began administering socalled convalescent plasma when donors were available. At an Ebola treatment center run by Doctors Without Borders in Conakry, Guinea, researchers devised a way to assess whether the treatment actually worked.

Unfortunately, it did not. A study in Thursday’s edition of the New England Journal of Medicine found that patients who were treated with convalescent plasma were 12% less likely to die than were patients who didn’t get the transfusions. However, that difference was small enough that the researchers said it could well have been due to chance.

The Ebola-Tx study was not a typical clinical trial, with some patients randomly assigned to receive plasma transfusions and other patients serving as untreated controls. The researchers planned to treat about 130 patients and compare them with a control group of patients who were treated in the same clinic before the donor plasma became available.

As it happened, doctors were able to procure plasma so quickly that there was no time to recruit this control group. So the researchers improvised a new control group consisting of 418 patients who were treated in the same clinic several months earlier.

In another surprise, the Ebola crisis waned before the researchers were able to give transfusions to 130 patients. So the trial ended early, with 84 patients included in the main analysis.

The researchers reported that 26 of the 84 patients died in the 16 days after getting a definitive diagnosis of Ebola infection. That amounted to a mortality rate of 31%.

For comparison, 158 of the 418 patients in the control group died in the 16 days after they were diagnosed. That was a mortality rate of 38%, but the 7 percentagepoint difference wasn’t large enough to be statistically significant.

Although the study didn’t confirm that this treatment worked as hoped, it did contain some good news. For instance, the researchers were able to get enough blood to make the treatment feasible. The transfusions were well tolerated by patients, with no cases of serious side effects.

In addition, the study results do not rule out the possibility that convalescent plasma can be a valuable treatment. Some groups of patients, such as pregnant women and children under 5, did much better than expected after getting the transfusions.