Germany's Robert Koch Institute head Reinhard Kurth believes that a vaccine against SARS, the severe acute respiratory syndrome that has been linked to at least 78 deaths around the world, will take at least three years to develop. According to Kurth, researchers are searching for conclusive evidence that the virus thought to be the cause of SARS [the coronavirus] is actually the source of the disease. Once that proof is found, Kurth said, a vaccine could be available within three to five years.