Inconclusive result from Ebola ZMapp trial

While study results show that patients taking new Ebola treatment ZMapp had a 40% reduced risk of death, authors say results did not meet statistical threshold for efficacy.

Ebola virus budding from cell

The severity of the Ebola outbreak in West Africa in 2014–2016 was impacted by a lack of proven therapeutic agents against the virus.

In March 2015, an open-label trial of a promising immune-based Ebola treatment called ZMapp was launched. It included 72 patients with confirmed Ebola infection who all received standard care (intravenous fluids, electrolytes, blood pressure and oxygen monitoring); half were randomly assigned to also receive three intravenous infusions of ZMapp every third day.

After 28 days, 22% of patients in the ZMapp group had died compared with 37% of those in the standard care alone group, equating to a 40% reduced risk of death.

However, reporting in The New England Journal of Medicine
(online, 13 October 2016), the researchers conclude that although ZMapp appeared beneficial, the result did not meet a prespecified statistical threshold for efficacy, potentially owing to inadequate trial recruitment.


[1] Prevail II writing group for the multi-national Prevail II study team. A randomised, controlled trial of ZMapp for Ebola virus infection. NEJM 2016;375:1448-1456. doi: 10.1056/NEJMoa1604330.

Last updated
Clinical Pharmacist, CP, November 2016, Vol 8, No 11;8(11):DOI:10.1211/PJ.2016.20201898

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