There has been a new step in the development of an effective vaccine against H5N1, the bird flu virus that's also dangerous to humans.
A preventative vaccine has been almost impossible to develop because of uncertainty over the final form of the virus when it mutates to a human pathogen.
According to virologists at the Erasmus Medical Center in Rotterdam, a vaccine currently being tested protects against different variants of the H5N1 virus, including new strains.
With the addition of a substance that stimulates the immune system, the vaccine response is improved.
Human trials (and trials in weasles, also susceptible to viruses) are currently underway.