The World Health Organization (WHO) has the power to declare a Public Health Emergency of International Concern (PHEIC) under the 2005 International Health Regulations. The criteria for declaring a PHEIC include evidence of viral genomic changes that provide an advantage for mammalian infection, and there have been instances of sustained transmission between other mammals. However, no sustained human-to-human transmission has been observed, but there is extensive ongoing transmission in avian populations, which has resulted in millions of bird deaths. The resolution criteria for the current market are based on whether the WHO declares that the spread of H5N1 constitutes a PHEIC before January 1, 2024. This declaration would signify an extraordinary event posing a public health risk to other countries through international spread of disease and potentially require a coordinated international response.