Don’t be alarmed. But the U.N. World Health Organization’s director-general has called a new SARS-like virus found in humans "a threat to the entire world." At the 66th World Assembly in Geneva, Margaret Chan said her "greatest concern" is encouraging countries to come together to tackle the coronavirus, which has killed 23 so far. The virus attacks the respiratory system, and its symptoms include fever and cough. "We understand too little about this virus when viewed against the magnitude of its potential threat," Chan said.