The World Health Organization on Wednesday declared the spread of mpox in multiple African countries a public health emergency of international concern, the second such declaration in the past two years called in response to transmission of the virus.
The latest decision came on the recommendation of a panel of experts convened to advise WHO Director-General Tedros Adhanom Ghebreyesus on the issue. It also follows a similar declaration Tuesday by the Africa Centres for Disease Control and Prevention.
A number of countries have reported cases of mpox this year — both the strain that was behind an earlier international outbreak, known as clade IIb, and another version of the virus that has evolved through person-to-person spread, clade Ib. The latter is responsible for one of the outbreaks currently underway in the eastern part of the Democratic Republic of the Congo and has spread beyond its borders.
“The detection and rapid spread of a new clade of mpox in eastern DRC, its detection in neighboring countries that had not previously reported mpox, and the potential for further spread within Africa and beyond is very worrying,” Tedros said in announcing the declaration. “In addition to other outbreaks of other clades of mpox in other parts of Africa, it’s clear that a coordinated international response is essential to stop this outbreak and save lives.”
Mpox is caused by a virus in the same family as smallpox, a virus that was declared eradicated in 1980. The virus, which is believed to be carried by small rodents in some countries in Africa, causes painful scarring rashes when contracted by people. People with mpox can also experience fever, muscle aches, headaches, and respiratory symptoms. The infection is especially dangerous in young children — most mpox deaths occur in children under the age of 5 — and people with compromised immune systems.
A public health emergency of international concern, or PHEIC, can be called in response to a disease event in which risk of cross-border spread is considered high and international cooperation will likely be needed to contain the threat. In this case, cross-border transmission has already occurred multiple times. The declaration of a PHEIC gives the WHO director-general the authority to issue what are known as temporary recommendations — guidance to countries on steps they should take to address the problem. The expert panel, known as an emergency committee, is still working to devise temporary recommendations to respond to this outbreak.
Some of the cases in Africa — notably in South Africa and in the Ivory Coast — are being caused by the version of the virus that sparked the earlier mpox PHEIC, which ran from late July 2022 through mid-May 2023. That strain of the virus, an evolved version of clade II viruses, became known as clade IIb. This earlier outbreak, which has involved extensive person-to-person transmission, is believed to have begun in Nigeria perhaps as early as 2015. It was the first time ongoing person-to-person spread of mpox was recorded. That transmission occurred primarily through sexual contact, which also had not been previously reported as a way the virus could be spread.
That outbreak, which was first detected in the United Kingdom in early May 2022, saw transmission mainly occur among gay, bisexual, and other men who have sex with men. It has not stopped, with nearly 100,000 cases reported by 116 countries since spread was first recognized. But in many places the rate of new infections has slowed considerably from the peak of the outbreak in the summer of 2022.
The trigger for the new PHEIC is a situation that was first observed last September in the DRC, one of the countries where mpox is endemic. The version of the virus that transmits in the DRC is known as clade I. It has been seen to cause more severe disease than clade II and clade IIb viruses.
Mpox transmission in the DRC has traditionally involved young children who become infected when they trap and handle the rodents believed to carry the virus. Infected children may also infect others within their households.
Many of the cases that the DRC has reported this year — more than 14,000, with over 500 deaths — involve this type of transmission, largely in the western part of the country.
But sexual transmission of clade I viruses has now also been observed, with a locus of spread detected in the eastern portion of the DRC, near where the country borders Uganda, Rwanda, and Burundi. People seen to have been infected in this outbreak include sex workers and their clients as well as men who have sex with men.
Person-to-person transmission has led to changes in the virus, which has now been dubbed clade Ib.
Transmission has spilled from this part of the DRC into Burundi, Kenya, Rwanda, and Uganda, which have reported roughly 90 cases in total in the past month. None of these countries has previously reported a case of mpox.
To date, clade 1 viruses have not been detected in the United States. But the Centers for Disease Control and Prevention has urged health care providers to consider mpox if they see patients with compatible symptoms who have been in the DRC or neighboring countries in the past 21 days, and to submit any samples taken for testing to the CDC.
Dimie Ogoina, a Nigerian infectious diseases expert who first reported what was going on with the emergence of clade IIb in his home country, was named chair of the new emergency committee.
Ogoina said a critical component of combatting these various outbreaks will be to better understand how the virus is spreading within different populations and countries, so that interventions tailored to those specific situations can be put in place. Among those interventions is the use of vaccines, of which there are limited global supplies. Before countries can decide how to use vaccine effectively, they need to understand how the virus is transmitting in their populations, noted Ogoina, who teaches at Niger Delta University.
“It’s very important for you to understand your outbreak for you to ultimately decide what groups of persons to vaccinate. And we have that gap in parts of Africa where we don’t fully understand the transmission dynamics and the risk factors for mpox,” he said.
The WHO said it has been informed that Bavarian Nordic, which makes one of the poxvirus vaccines that is used to protect against mpox, has about a half million doses on hand at present. And Tim Nyugen, with WHO’s department of high impact events preparedness, said the company has indicated another 2.4 million doses of the two-dose vaccine, sold as Jynneos, could be made by the end of the year — if firm purchase orders are placed. The company has said it could make another 10 million doses next year, if firm orders are placed, Nyugen said.
He said the WHO is also working with KM Biologics, the maker of another vaccine, known as LC16, which has not been commercialized but is made for the government of Japan. Nyugen said Japan has been very generous in the past in donating doses of LC16.
The U.S. government has already announced it will donate 50,000 doses of vaccine from the Strategic National Stockpile to DRC. Maria Van Kerkhove, WHO’s acting director of epidemic and pandemic preparedness and prevention, called on countries that have vaccine doses they can donate to work with the global health agency. “We need to have good visibility on what is available and how those [doses] could be potentially used,” she said.
The declaration of a PHEIC elevates the attention the issue should receive in the world’s capitals. It is sometimes thought to help raise money for a particular health problem, although that is not a given. In the previous mpox PHEIC, the WHO put out an appeal for nearly $34 million to help it and affected countries combat the outbreak, but no donors stepped forward.
Van Kerkhove said there has already been a regional request for $15 million to help with the current response, but she warned the number will rise.
Anne Rimoin, an mpox expert at the University of California, Los Angeles, just returned from the DRC, where she has studied the virus for years. She suggested getting this situation under control will be a daunting task, both because the conditions that lead to spillovers — when someone contracts the virus from an animal — are poorly understood, and because of the populations in which cases occur.
“We’re just picking up pieces of what’s actually happening because surveillance is not robust,” Rimoin told STAT. “We’re dealing with vulnerable and hard-to-reach populations … whether you’re talking about [infected people in] remote rural areas or men who have sex with men or sex workers.”
Many questions remain about the species of animals that carry mpox and why spillover events are more numerous in some years than in others. In recent years there has been a high number of reported spillovers, which may in part be due to improvements in surveillance, but could also represent true increases driven by as-yet-unknown factors, she said.
“These are the questions that have long been unanswered, because it’s very difficult to be able to do this kind of work. I mean, it’s really needle-in-a-haystack work,” Rimoin said.
This story has been updated with vaccine and other information.
