Expanding the scope of the IHR beyond reporting of 3 diseases to reporting of any public health emergency of international concern required an algorithm to assist in identifi cation of such events. The resulting decision instrument (see [8] , Annex 2, p. 43) identifi es a limited set of criteria for use by member states for fulfi lling the obligation to determine whether an event occurring within their territory might constitute a public health emergency of international concern and therefore require formal notifi cation to WHO within 24 hours of assessment. Essentially, the events that must be reported are those that fulfi ll at least 2 of the following criteria: