The viral disease mpox, formerly known as monkeypox, has become a worldwide threat once again. On Wednesday afternoon, the World Health Organization declared a public health emergency of international concern, or PHEIC, over mpox, citing a resurgence of cases across Africa and the emergence of a new, deadlier variant of the virus.
Mpox is caused by a virus closely related to the now-extinct smallpox virus. It has long been considered a zoonotic disease, one that primarily spreads from animals (likely rodents, not monkeys) to humans. But that changed in early 2022, when the virus began to cause widespread human-to-human outbreaks outside Africa. These outbreaks spanned the globe, with more than 90,000 cases in over 100 countries documented. The WHO issued its first PHEIC on mpox in July 2022, which was also the first such declaration made since the arrival of covid-19.
Mpox infections usually cause flu-like illness, headaches and distinctive bumpy rashes or lesions throughout the body, with symptoms appearing within 21 days of exposure. People can potentially spread the infection to others several days before they feel sick, and remain contagious until their rash fully heals, which can take two to four weeks. The virus can theoretically spread through any kind of direct contact. But during the 2022 outbreaks, it was largely transmitted sexually between gay and bisexual men. Luckily, the strains that spread belonged to a less fatal lineage of the virus (clade II), with only around 150 deaths reported in 2022.
Scientists had already developed a vaccine for mpox prior to these outbreaks (thanks to its close resemblance to smallpox). Vaccination and awareness campaigns in high-risk communities have helped drive down cases of mpox since 2022, with the WHO’s first PHEIC on mpox ending in May 2023. But experts have feared that the virus could continue to cause large outbreaks or mutate further to become more dangerous—fears that have since become reality.
This year, there have been more than 14,000 suspected or confirmed cases and 524 deaths tied to mpox, according to the Associated Press. These cases and deaths have been found in 13 countries, though most have been concentrated in the Democratic Republic of the Congo. These outbreaks are tied to an established lineage of the virus (clade I), but a newer variant (clade Ib) more lethal than the strains that emerged globally in 2022 now appears to be spreading widely, with a mortality rate hovering around 3 to 4%. As in 2022, the initial outbreaks seem to have spread mainly through sexual contact, but more recently, doctors have reported a noticeable rise of cases affecting younger children, health care workers, and households. That raises the real possibility that the virus can now spread easily enough through other forms of direct contact.
Last week, the Africa Centers for Disease Control and Prevention declared a public emergency over the outbreaks. But while most of the danger has so far been confined to Africa, the WHO’s declaration signals that the rest of the world isn’t necessarily safe from mpox.
“The emergence of a new clade of mpox, its rapid spread in eastern DRC, and the reporting of cases in several neighboring countries are very worrying. On top of outbreaks of other mpox clades in DRC and other countries in Africa, it’s clear that a coordinated international response is needed to stop these outbreaks and save lives,” said WHO director-general Tedros Adhanom Ghebreyesus in the WHO’s announcement of the decision.
While the U.S. supply of the most widely used mpox vaccine (Jynneos) has recently been replenished, the same isn’t true for the countries currently most affected by these outbreaks. Experts have warned that initial vaccine supplies are likely to fall well short of the 3 million doses planned to be available in Africa by the end of the year.
The WHO has already taken steps to accelerate the emergency approval of vaccines in lower-income countries that have no approved vaccines, and it has released $1.45 million from its emergency contingency fund to address the crisis. The WHO also is working to coordinate vaccine donations from other countries and pharmaceutical companies. But these steps alone certainly won’t be enough. The organization estimates that at least $15 million will be immediately needed to fund surveillance, preparedness and response activities, and it plans to appeal to donors for more funding.
