For the emergency created by the epidemic of influence of the pigs in Mexico it was correct not to create alarmisms being victims of a bad information. The possibility that the virus arrives in other parts of the world is real as for all the types of influence virus. In order that a strain has a wide distribution, its antigenic characteristics must ensure that it escapes the neutralization of antibodies of the host and of the surrounding population. The discovery of a new, biologic Host-Defen...