New Ebola vaccine may have 100% efficacy

Developing a vaccine against Ebola has been a priority since the largest recorded epidemic of the disease in West Africa began in summer 2014. With funding primarily from the World Health Organization, a new vaccine against the Zaire Ebola strain was tested in a phase III trial involving 7,651 people in Guinea.

In a pr
ocess called ‘ring vaccination’, new cases of Ebola were laboratory-confirmed and all of the individual’s contacts, as well as contacts of contacts, identified. When contacts were vaccinated immediately, there were no new cases of Ebola. However, in the control group, vaccination was delayed
by 21 days and there were 16 cases. This suggests a vaccine efficacy of 100% (95% confidence interval 74·7–100·0;
P
=0·0036).

The vaccine seems to be highly efficacious and safe, conclude the authors of the study in
The Lancet
(online, 31 July 2015)
^[1]
.