A new Ebola vaccine that was tested on humans during the last days of the West African epidemic was found to be 100 percent effective in providing protection to those who received it right after exposure to the deadly virus.

Vaccine Highly Effective In Providing Protection Against Ebola Virus

The experimental vaccine, known as rVSV-EBOV, was given to about 5,800 people last year in Guinea as the outbreak wanes. All of the participants had some contact with a new Ebola patient and received the vaccine right away or three weeks after exposure.

After 10 days, no Ebola case was reported in those who were immediately vaccinated and only 23 of those whose vaccination was delayed developed the disease.

"The results add weight to the interim assessment that rVSV-ZEBOV offers substantial protection against Ebola virus disease, with no cases among vaccinated individuals from day 10 after vaccination in both randomised and non-randomised clusters," investigators reported in The Lancet on Thursday.

The vaccine was developed by the Canadian government and is now licensed to pharmaceutical company Merck & Co., which is expected to seek regulatory approval in both United States and Europe by next year. The clinical study of the vaccine was led by the World Health Organization (WHO).

An emergency stockpile of 300,000 has already been produced so the vaccine can be used in case an outbreak breaks out again.

"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 outbreak hits, we will not be defenseless," said Marie-Paule Kieny, WHO's assistant director-general for health systems and innovation, who was also part of the clinical study. "The world can't afford the confusion and human disaster that came with the last epidemic."

More Work Needed For Better Ebola Vaccines

The vaccine, however, is far from perfect. It appears to be effective only against one of the two most common strains of the hemorrhagic virus. It may not also provide long-lasting protection. Some of those who received the vaccine also reported of unwanted side effects such as headaches and joint pain.

There is clearly a need for more work on Ebola vaccines but health experts welcome the findings of the clinical study. They hailed the vaccine as a step to the right direction in preventing the occurrence of fatal Ebola outbreaks such as the one that killed thousands in West Africa.