On 14 August 2024, the World Health Organization declared mpox a public health emergency of international concern for the second time in two years. The trigger was a sharp rise in cases of a new, more transmissible strain known as clade 1b, which had spread across the Democratic Republic of Congo and into neighbouring countries including Burundi, Kenya, Rwanda and Uganda.
Unlike the clade 2 outbreak of 2022 that primarily spread through close contact among men who have sex with men, clade 1b appeared to transmit through close household and sexual contact more broadly, including among children, and carried a higher documented fatality rate. Vaccines and treatments existed but were scarce in the African countries where they were most needed, a pattern the WHO and public health experts denounced as a repeat of historic inequities.
The declaration mobilized funding and vaccine donations, and manufacturers ramped up production of the Jynneos vaccine. The episode reinforced a painful lesson from covid-19: that an outbreak ignored at its source will eventually travel, and that the gap between those with access to protection and those without remains the single most important factor in how fast a disease spreads.