An experimental vaccine has proved to provide high protection against the deadly Ebola virus, according to the results published in weekly general medical journal The Lancet. The vaccine, manufactured by Merk, Sharpe & Dohme, is called rVSV-ZEBOV, and was studied in a trial involving 11,841 people in Guinea in 2015. The trial was led by the World Health Organisation, in collaboration with Guinea’s Ministry of Health, Medecins sans Frontieres and the Norwegian Institute of Public Health.

More than 11,300 people died in an Ebola outbreak in West Africa between 2013-2016, according to WHO. “When the next Ebola outbreak hits, we will not be defenceless,” said Dr Marie-Paule Kieny, WHO’s Assistant Director-General for Health Systems and Innovation and one of the lead researchers in the trial.

Gavi, the Vaccine Alliance, in January provided Merck with $5 million to buy 3,00,000 doses of this vaccine for future Ebola outbreaks. Merck has also submitted the vaccine to WHO’s Emergency Use and Assessment Listing procedure.

How it was tested:

The trial took place in the coastal region of Basse-Guinee and a “ring vaccination” approach was used by the researchers, which is the same method used to eradicate small pox. When a patient was diagnosed with Ebola, the research team traced all people who may have been in contact with the individual in the last three weeks. Clusters or rings were formed with these identified individuals who were offered rVSV-ZEBOV immediately or after a 3-week delay. The trial was open to everyone including children older than 6 years.

These individuals were observed for 30 minutes after the vaccination and at repeated home visits up to 12 weeks later. Almost half the patients reported mild symptoms of the disease, however they recovered within days without any long-term effects, WHO said. The results showed that among the 5,837 people who received the vaccine, no Ebola cases were recorded 10 days or more after the vaccination, The Lancet said.