LONDON (AP) — The expanding monkeypox outbreak in more than 70 countries is an “extraordinary” situation that qualifies as a global emergency, the World Health Organization chief said Saturday, a declaration that could spur further investment in treating the once-rare disease and worsen the scramble for scarce vaccines.

A global emergency is WHO’s highest level of alert but the designation does not necessarily mean a disease is particularly transmissible or lethal. Similar declarations were made for the Zika virus in 2016 in Latin America and the ongoing effort to eradicate polio, in addition to the COVID-19 pandemic and the 2014 Ebola outbreak in West Africa.

WHO Director-General Tedros Adhanom Ghebreyesus made the decision on calling monkeypox a global emergency despite a lack of consensus among experts on the UN health agency’s emergency committee, saying he acted as “a tiebreaker.” It was the first time a UN health agency chief has unilaterally made such a decision without an expert recommendation.

“We have an outbreak that has spread around the world rapidly through new modes of transmission, about which we understand too little,” Tedros said. “I know this has not been an easy or straightforward process and that there are divergent views among the members” of the committee.

WHO’s emergencies chief, Dr Michael Ryan, said the director-general decided to declare monkeypox a global emergency to ensure the world takes the current outbreaks seriously.

Although monkeypox has been established in parts of central and west Africa for decades, it was not known to spark large outbreaks beyond the continent or to spread widely among people until May, when authorities detected dozens of epidemics in Europe, North America and elsewhere.

Last month, WHO’s expert committee said the monkeypox outbreak did not yet amount to an international emergency, but the panel convened this week to reevaluate the situation.

According to the US Centers for Disease Control and Prevention, more than 16,000 cases of monkeypox have been reported in 74 countries since about May. To date, monkeypox deaths have only been reported in Africa, where a more dangerous version of the virus is spreading, mainly in Nigeria and Congo.

In Africa, monkeypox mainly spreads to people by infected wild animals like rodents in limited outbreaks that typically have not crossed borders. In Europe, North America and elsewhere, however, monkeypox is spreading among people with no links to animals or recent travel to Africa.

WHO’s top monkeypox expert, Dr Rosamund Lewis, said this week that 99 per cent of all the monkeypox cases beyond Africa were in men and that of those, 98 per cent involved men who have sex with men. Experts suspect the monkeypox outbreaks in Europe and North America were spread via sex at two raves in Belgium and Spain.

“Although I am declaring a public health emergency of international concern for the moment, this is an outbreak that is concentrated among men who have sex with men, especially those with multiple sexual partners,” Tedros said. “That means that this is an outbreak that can be stopped with the right strategies in the right groups.”

Britain recently downgraded its assessment of monkeypox after seeing no signs of widespread transmission beyond men who are gay, bisexual or have sex with other men and noting the disease does not spread easily or cause severe illness.

Before Saturday’s announcement, Michael Head, a senior research fellow in global health at Southampton University, said it was surprising WHO hadn’t already declared monkeypox a global emergency, explaining that the conditions were arguably met weeks ago.

Some experts had questioned whether such a declaration would help, arguing the disease isn’t severe enough to warrant the attention and that rich countries battling monkeypox already have the funds to do so. Most people recover without needing medical attention, although the lesions may be painful.

Head said WHO’s emergency declaration could help donors like the World Bank make funds available to stop the outbreaks both in the West and in Africa.

In the US, some experts have speculated whether monkeypox might be on the verge of becoming an entrenched sexually transmitted disease in the country, like gonorrhea, herpes and HIV.

“The bottom line is we’ve seen a shift in the epidemiology of monkeypox where there’s now widespread, unexpected transmission,” said Dr Albert Ko, a professor of public health and epidemiology at Yale University. “There are some genetic mutations in the virus that suggest why that may be happening, but we do need a globally-coordinated response to get it under control.”

Ko called for testing to be immediately scaled up, saying that like the early days of COVID-19, there are significant gaps in surveillance.

“The cases we are seeing are just the tip of the iceberg,” he said. “The window has probably closed for us to quickly stop the outbreaks in Europe and the US, but it’s not too late to stop monkeypox from causing huge damage to poorer countries without the resources to handle it.”

WHO’s Tedros called for the world to “act together in solidarity” regarding the distribution of treatments, test and vaccines. The UN agency has previously said it’s working to create a vaccine-sharing mechanism for the most-affected countries. And unlike the numerous companies that made COVID-19 vaccines, there is only one maker of the vaccine used against monkeypox, Denmark’s Bavarian Nordic.

Dr Placide Mbala, a virologist who directs the global health department at Congo’s Institute of National Biomedical Research, said he hoped any global efforts to stop monkeypox would be equitable. Although countries including Britain, Canada, Germany and the US have ordered millions of vaccine doses, none have gone to Africa.

“The solution needs to be global,” Mbala said, adding that any vaccines sent to Africa would be used to target those at highest risk, like hunters in rural areas.

“Vaccination in the West might help stop the outbreak there, but there will still be cases in Africa,” he said. “Unless the problem is solved here, the risk to the rest of the world will remain.”