China's SARS Molecular Epidemiology Consortium studied last year's outbreak of severe acute respiratory syndrome (SARS) and its genetic evolution process. The data could aid in future vaccine development, the researchers say. The findings, published in the most recent issue of the journal Science, show that SARS is animal-based and jumps between animals and humans. The data suggests that the virus that causes SARS underwent significant genetic changes that resulted in easier human-to-human spread of the disease.