Scientists struggle to understand swine flu virus (AP)

AP - Mexico's health secretary may have thought he was allaying fears about swine flu when he suggested that the nation's swine flu death rate was 6 or 7 percent. In reality, that would mean a monstrous killer virus — and no experts are close to saying that. The secretary's comment reflects how much remains unknown about the new flu virus — most notably how lethal it is and why it seems so much deadlier in Mexico than anywhere else.