Tierney presents convincing evidence that Neel and Chagnon, on their trip to the Yanomami in 1968, greatly exacerbated, and probably started, the epidemic of measles that killed "hundreds, perhaps thousands" (Tierney's language-the exact figure will never be known) of Yanomami. The epidemic appears to have been caused, or at least worsened and more widely spread, by a campaign of vaccination carried out by the research team, which used a virulent vaccine (Edmonson B) that had been counter-indicated by medical experts for use on isolated populations with no prior exposure to measles exactly the Yanomami situation). Even among populations with prior contact and consequent partial genetic immunity to measles, the vaccine was supposed to be used only with supportive injections of gamma globulin.