Excellent news as 2016 draws to a close: Scientists say they've created an Ebola vaccine that appears to be 100% effective. In a trial involving more than 11,000 at-risk people in Guinea, nobody given the vaccine developed the virus after a 10-day incubation period, researchers wrote in a study published in the Lancet medical journal Thursday. "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 defenseless," says the study's lead author, World Health Organization Assistant Director-General Marie-Paule Kieny. Only two patients suffered serious reactions to the vaccine, and no long-term problems were reported. Researchers are still trying to determine how long the vaccine is effective for.
The experimental vaccine, named rVSV-ZEBOV, was given to patients as the West African outbreak of the deadly disease was still raging in 2015. Researchers say they used the same "ring vaccination" approach that helped wipe out smallpox, the Washington Post reports. They traced each ring of people who may have come in contact with an infected person, vaccinating a total of 117 clusters of people with an average of 80 people in each one. "After 40 years we appear to now have an effective vaccine for Ebola virus disease to build upon," virologist Thomas Geisbert wrote in a commentary accompanying the study. CNN reports that the vaccine, licensed by US firm Merck, has been fast-tracked for approval by regulators. The company has promised to have 300,000 doses ready in case of emergency. (Read more Ebola vaccine stories.)