A
public health emergency of international concern is a formal declaration by the World Health Organization (WHO) of "an extraordinary event which is determined to constitute a public health risk to other States through the international spread of disease and to potentially require a coordinated international response", formulated when a situation arises that is "serious, sudden, unusual, or unexpected", which "carries implications for public health beyond the affected state's national border" and "may require immediate international action". Under the 2005 International Health Regulations (IHR), states have a legal duty to respond promptly to a PHEIC. The declaration is publicized by an IHR Emergency Committee (EC) of international experts, which was developed following the 2002â2004 SARS outbreak.