A top federal health official worries that Americans have been "lulled into a false sense of security" about the threat of smallpox, because biological agents have not yet been found in Iraq. The need to prepare for an attack is just as urgent, Dr. Julie Gerberding, director of the Centers for Disease Control and Prevention, said Wednesday. Federal officials must work hard to explain this to state and local health officials, who have been slow to get vaccinated against smallpox, partly because they do not believe the virus poses a real threat, she added. "It concerns me very much that...