The World Health Organization on Wednesday declared the ongoing mpox outbreak in Africa a global health emergency.

WHO convened its emergency committee amid concerns that a deadlier strain of the virus, clade Ib, had reached four previously unaffected countries in Africa. This strain had previously been contained to the Democratic Republic of Congo.

The independent experts met virtually Wednesday to advise WHO Director-General Tedros Adhanom Ghebreyesus on the severity of the outbreak. After that consultation, he announced that he had declared a public health emergency of international concern — the highest level of alarm under international health law.

“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,” he said.

“The emergency committee met and advised me that the situation constitutes a public health emergency of international concern. I have accepted that advice.”

Also known as a PHEIC, this is a status given by WHO to “extraordinary events” that pose a public health risk to other countries through the international spread of disease. These outbreaks may require a coordinated international response, according to the organization.

“It was unanimous that the current outbreak of mpox, upsurge of mpox, is an extraordinary event,” committee Chair Dimie Ogoina said. “What we have in Africa is the tip of the iceberg. … We are not recognizing, or we don’t have the full picture of, this burden of mpox.”

The Africa Centres for Disease Control and Prevention declared the outbreak a public health emergency of continental security on Tuesday, the first such declaration by the agency since its inception in 2017.

Since the beginning of the year, more than 17,000 mpox cases and more than 500 deaths have been reported in 13 countries in Africa, according to the Africa Centers for Disease Control and Prevention, which classifies the outbreak as a “very high risk event.” The highest number of cases — more than 14,000 — is in the DRC, which reported 96% of confirmed cases this month.

Mpox, formerly known as monkeypox, is a viral disease that can spread easily between people and from infected animals. It can spread through close contact such as touching, kissing or sex, as well as through contaminated materials like sheets, clothing and needles, according to WHO. Symptoms include a fever, a painful rash, headache, muscle and back pain, low energy and enlarged lymph nodes.

For decades, the disease had largely been found in Central and West Africa, but it also began spreading in Europe and North America in 2022. WHO previously declared the spread of mpox a global health emergency in July 2022 and ended that declaration in May 2023.

Mpox is characterized by two genetic clades, I and II. A clade is a broad grouping of viruses that has evolved over decades and is a genetic and clinically distinct group. Clade II was responsible for the 2022 outbreak, but clade Ib causes more severe disease.

“But we are not dealing with one outbreak of one clade; we are dealing with several outbreaks of different clades in different countries with different modes of transmission and different levels of risk,” Tedros clarified.

No cases of clade I mpox have been identified in the United States, the US Centers for Disease Control and Prevention says, but it is monitoring the situation, and the US government has offered funding, assistance and vaccines to WHO and the DRC to support efforts in Africa.

The CDC recommended last week that people in the US who are exposed to or at high risk of catching mpox should get vaccinated.

WHO officials said last week that the virus could be contained “quite straightforwardly, if we do the right things at the right time.” They are further calling for international cooperation in financing and organizing efforts to quell the outbreak and funding research to better understand clade Ib and its spread.

“It’s clear that a coordinated international response is essential to stop these outbreaks and save lives,” Tedros said Wednesday.

The organization has signed off on the Emergency Use Listing process for both mpox vaccines and developed a regional response plan requiring $15 million, with $1.5 million released from the WHO Contingency Fund for Emergencies.

Half a million doses of the vaccine are in stock, and another 2.4 million could possibly be produced by the end of the year, according to Tim Nguyen of the WHO Health Emergencies Program. The DRC and Nigeria will be the first to receive these vaccines, African Regional Emergency Director Dr. Abdou Salam Gueye added.

The organization emphasized that vaccines are only part of the response; containing the spread will also require increased surveillance, diagnostics and research to fill “gaps in understanding.”

“We can stop transmission of mpox with a concerted effort using multiple approaches,” said Dr. Maria Van Kerkhove, director of WHO’s Department of Epidemic and Pandemic Preparedness and Prevention.

“There’s a lot of uncertainty. … We have an opportunity right now to really leverage this time and support our member states to support the research that needs to be done to understand this.”