Final trial results confirm Ebola vaccine provides high protection against disease

| December 22, 2016

An experimental Ebola vaccine was highly protective against the deadly virus in a major

trial in Guinea, according to results published today in The Lancet. The vaccine is the

first to prevent infection from one of the most lethal known pathogens, and the findings

add weight to early trial results published last year.

The vaccine, called rVSV-ZEBOV, was studied in a trial involving 11,841 people in Guinea

during 2015. Among the 5,837 people who received the vaccine, no Ebola cases were recorded

10 days or more after vaccination. In comparison, there were 23 cases 10 days or more

after vaccination among those who did not receive the vaccine.

The trial was led by the World Health Organization, together with Guinea's

Ministry of Health, Medecins sans Frontieres and the Norwegian Institute of Public Health,

in collaboration with other international partners.

While these compelling results come too late for those who lost their lives during

West Africa's Ebola epidemic, they show that when the next Ebola outbreak hits, we will

not be defenceless,rdquo; said Dr Marie-Paule Kieny, WHO's Assistant Director-General for

Health Systems and Innovation, and the study's lead author.

The vaccine's manufacturer, Merck, Sharpe amp; Dohme, this year received

Breakthrough Therapy Designation from the United States Food and Drug Administration and

PRIME status from the European Medicines Agency, enabling faster regulatory review of the

vaccine once it is submitted.

Since Ebola virus was first identified in 1976, sporadic outbreaks have been

reported in Africa. But the 2013-2016 West African Ebola outbreak, which resulted in more

than 11,300 deaths, highlighted the need for a vaccine.

The trial took place in the coastal region of Basse-Guineacute;e, the area of

Guinea still experiencing new Ebola cases when the trial started in 2015. The trial used

an innovative design, a so-called ring vaccinationrdquo; approach - the same method used

to eradicate small pox.

When a new Ebola case was diagnosed, the research team traced all people who may

have been in contact with that case within the previous 3 weeks, such as people who lived

in the same household, were visited by the patient, or were in close contact with the

patient, their clothes or linen, as well as certain contacts of contactsrdquo;. A total of

117 clusters (or ringsrdquo;) were identified, each made up of an average of 80 people.

Initially, rings were randomised to receive the vaccine either immediately or

after a 3-week delay, and only adults over 18 years were offered the vaccine. After

interim results were published showing the vaccine's efficacy, all rings were offered the

vaccine immediately and the trial was also opened to children older than 6 years.

In addition to showing high efficacy among those vaccinated, the trial also shows

that unvaccinated people in the rings were indirectly protected from Ebola virus through

the ring vaccination approach (so called herd immunityrdquo;). However, the authors note

that the trial was not designed to measure this effect, so more research will be needed.

Ebola left a devastating legacy in our country. We are proud that we have been

able to contribute to developing a vaccine that will prevent other nations from enduring

what we enduredrdquo; said Dr KeIuml;ta Sakoba, Coordinator of the Ebola Response and

Director of the National Agency for Health Security in Guinea.

To assess safety, people who received the vaccine were observed for 30 minutes

after vaccination, and at repeated home visits up to 12 weeks later. Approximately half

reported mild symptoms soon after vaccination, including headache, fatigue and muscle pain

but recovered within days without long-term effects. Two serious adverse events were

judged to be related to vaccination (a febrile reaction and one anaphylaxis) and one was

judged to be possibly related (influenza-like illness). All three recovered without any

long term effects.

It was not possible to collect biological samples from people who received the

vaccine in order to analyse their immune response. Other studies are looking at the immune

response to the vaccine including one conducted in parallel to the ring trial among

frontline Ebola workers in Guinea.

This both historical and innovative trial was made possible thanks to exemplary

international collaboration and coordination, the contribution of many experts worldwide,

and strong local involvement,rdquo; said Dr John-Arne Roslash;ttingen, specialist director

at the Norwegian Institute of Public Health, and the chairman of the study steering group.

In January, GAVI, the Vaccine Alliance provided US$5 million to Merck towards the

future procurement of the vaccine once it is approved, prequalified and recommended by

WHO. As part of this agreement, Merck committed to ensure that 300,000 doses of the

vaccine are available for emergency use in the interim, and to submit the vaccine for

licensure by the end of 2017. Merck has also submitted the vaccine to WHO's Emergency Use

and Assessment Listing procedure, a mechanism through which experimental vaccines,

medicines and diagnostics can be made available for use prior to formal licensure.

Additional studies are ongoing to provide more data on the safety of the vaccine

in children and other vulnerable populations such as people with HIV. In case of Ebola

flare-ups prior to approval, access to the vaccine is being made available through a

procedure called compassionate userdquo; that enables use of the vaccine after informed

consent. Merck and WHO's partners are working to compile data to support license


The rapid development of rVSV-ZEBOV contributed to the development of WHO's Ramp;D

Blueprint, a global strategy to fast-track the development of effective tests, vaccines

and medicines during epidemics.

Source: World Health Organization (WHO).NOTES TO EDITORS


Category: Technology

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