rapidly spread in the region, then to Hong Kong, Vietnam, and Singapore. Focal outbreaks were also reported in other countries by travelers from the endemic region who became ill when they returned home. The virus was named SARS-CoV. Two facts about this virus are critical: person-to-person spread occurred readily, including in the health care workers exposed to the patients, and the disease was responsible for a high mortality rate, particularly for patients with underlying pulmonary disease (i.e., 50% mortality) and in the elderly. By Maleeha Fatima