The Lancet: Zika virus and microcephaly: why is this situation a PHEIC?
David L. Heymann, head and senior fellow at the Chatham House Center on Global Health Security and professor of infectious disease epidemiology at the London School of Hygiene & Tropical Medicine, and colleagues, all members of the WHO Emergency Committee on Zika virus

“…Representatives from four countries (Brazil, El Salvador, France, and the USA) that have had either outbreaks or importations of Zika virus, and a group of arbovirus specialists, took part in the meeting. … [W]e were able to discern as a committee, and then agree unanimously in an initial poll, that the clusters of microcephaly and neurological disorders, and their possible association with the Zika virus, constituted a PHEIC. … The first recommendation of the PHEIC was to call for standardised and enhanced surveillance of microcephaly in areas of known Zika virus transmission. … Our second recommendation under the PHEIC is for increased research into the etiology of confirmed clusters of microcephaly and neurological disorders to determine whether there is a causative link to Zika virus, other factors, and cofactors. … After our discussion on the PHEIC, there was unanimous agreement to make recommendations for precautionary measures to prevent arboviral infection. … The Director-General declared the Ebola outbreaks a PHEIC because of what science knew about the Ebola virus from many years of research during outbreaks in the past, whereas she declared the current PHEIC because of what is not known about the current increase in reported clusters of microcephaly and other disorders, and how this might relate to concurrent Zika outbreaks…” (2/20).