Severe acute respiratory syndrome (SARS) emerged in 2002 as a severe and highly contagious infectious disease that rapidly spread to a number of different countries. The collaborative efforts of the global scientific community have provided, within a short period of time, substantial insights into the molecular biology and immunology of SARS-CoV. Although the outbreak has been contained, there is continuous concern that the virus may resurface into the human population through seasonal changes, animal reservoirs or laboratory accidents. The severe morbidity and mortality associated with SARS make it imperative that an effective vaccine be developed to prevent reemergence and epidemics in the future.