Report: Ebola vaccine ‘promising’
GENEVA — A new World Health Organization report amid the largest outbreak of Ebola ever recorded describes “a promising Ebola vaccine candidate,” identified by a trial in Guinea.
The vaccine, a recombinant, replication-competent vesicular stomatitis virus-based vaccine with a surface glycoprotein of Zaire Ebolavirus (rVSV-ZEBOV) creates “a rapid immune response against the Ebola virus surface protein,” according to the report.
The trial, whose pilot phase began March 23, was modeled after the ring vaccination technique used for combating the smallpox epidemic in the 70s, and oversaw the vaccination of a cluster of adults aged 18 years or older who were at high risk of infection. Pregnant or breastfeeding people were not eligible for the study.
The population, which totaled to 7,651 people (or 90 clusters), included patients with confirmed cases of Ebola and their contacts — people who, within the last 21 days, lived in the same household or were in close physical proximity to Ebola patients’ body or body fluids, linen or clothes.
The study then randomly allocated the population to either immediate or delayed (21 days later) vaccination. Over half (about 54%) of the patients were randomly assigned to immediate vaccination and about 46% were randomly assigned to delayed vaccination.
In the first group, there were no cases of Ebola with symptom onset at least 10 days after receiving the vaccine, whereas there were 16 cases of Ebola in the delayed vaccination group, resulting in a vaccine efficacy of 100%.
From six days post-vaccination, no new cases of Ebola were diagnosed in people who were vaccinated from either the immediate or delayed groups, according to the report.
Vaccine effectiveness was 75.1% at the cluster level, with the inclusion of all adults eligible for vaccination, and 76.3% for all eligible and non-eligible adults, the report said.
“The results of this interim analysis indicate that rVSV-ZEBOV might be highly efficacious and safe in preventing Ebola virus disease, and is most likely effective at the population level when delivered during an Ebola virus disease outbreak via a ring vaccination strategy,” the report said.
Dr. Margaret Chan, the director general of the WHO, declared the Ebola outbreak a “crisis for international peace and security,” according to The New York Times.
Since March 2014, there have been 27,705 reported cases of Ebola and 11,269 reported deaths from the disease. No licensed vaccines are currently available for treatment.