a new ebola jab is being given to people living in the west african countries most badly hit by the virus .
scientists hope that immunisation is possible with just one injection after ` highly promising results ' in the first 138 healthy adults who were vaccinated with various doses that the vaccine , developed in canada , is based on an animal virus called vesicular stomatitis virus -lrb- vsv -rrb- that is combined with a portion of the protein covering of the ebola virus that