The World Health Organization (WHO) declared mpox to be a public health emergency of international concern (PHEIC) on Wednesday

"Today, the Emergency Committee met and advised me that in its view, the situation constitutes a public health emergency of international concern. I have accepted that advice," said WHO Director-General Dr. Tedros Adhanom Ghebreyesus during a media briefing on Wednesday.

In the U.S, there have been 1,634 cases of mpox reported so far this year, according to data from the U.S. Centers for Disease Control and Prevention (CDC).

That's more than double the number of national cases seen at the same time last year but significantly lower than those seen during a U.S. mpox outbreak in 2022, CDC data shows.

PHEICs were most recently declared for the COVID-19 pandemic and the previous mpox outbreak of 2022.

Although mpox is endemic to parts of Central and Western Africa, cases have been rising dramatically in the Democratic Republic of the Congo (DRC).

This year, there have already been more than 14,000 mpox cases and 524 deaths reported in the DRC, according to the WHO.

There are two types of mpox: clade I and clade II, with clade roughly meaning they are descended from a common ancestor organism. While clade I has caused small, localized outbreaks in the DRC for years, researchers identified a clade I variant, known as clade Ib, that seems to spread mainly through sexual contact and appears to be behind the outbreak in the DRC.

Tedros said the detection of clade Ib in neighboring African countries that have never reported mpox cases before – including Burundi, Kenya, Rwanda and Uganda – led him to convene a meeting of the WHO's emergency committee.

"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 during the briefing.

On Monday, the Africa Centres for Disease Control and Prevention (Africa CDC) – the continent's top health agency – declared mpox a public health emergency of continental security (PHECS) – the first such declaration since the Africa CDC's inception in 2017, according to the agency.

On the same day, the WHO published a report that found there were a total of 934 new laboratory confirmed cases of mpox and four deaths from 26 countries in the month of June, "illustrating continuing transmission of mpox across the world."

There have been no cases of clade I mpox reported outside Central and Eastern Africa at this time, including in the U.S., according to the CDC. The risk of the type of mpox circulating in the DRC is low to the American public, according to the CDC.

Currently, the JYNNEOS vaccine, a two-dose vaccine approved by the Food and Drug Administration to prevent smallpox and mpox, is the only vaccine being used in the U.S. to prevent mpox. Data from Africa has shown two doses of JYNNEOS are at least 85% effective in preventing mpox infection.