Mpox – What it is, and what it is not

The World Health Organization (WHO) and Africa Centres for Disease Control and Prevention (ACDC) have declared that an ongoing outbreak of mpox in Africa is both a continental and global health emergency. The declaration by the WHO of a Public Health Emergency of International Concern, or PHEIC, is the second time in two years that mpox has been classified as an international emergency.

Using ‘Answer the Public’, CEPI analysed some of the most frequently asked online questions about mpox across Sweden, Kenya, Canada and Brazil. These were among the countries with the highest numbers of people searching online for information about mpox over the past 12 months, according to Google Trends at the time of publishing.

Those questions—and CEPI’s answers—are below.
 

What is mpox and how dangerous is it? Could it kill you?

Mpox is a contagious infectious disease caused by the mpox virus, which is a member of the Poxvirus family. There are two different known forms, or clades, of the mpox virus known as clade I and clade II. Clade I usually causes a higher percentage of infected people to get severely sick or die compared to clade II. The first recorded human case of mpox, previously known as Human Monkeypox, was in the Democratic Republic of Congo (DRC) in 1970.

Most people infected with mpox suffer with flu-like symptoms such as fever, headache, muscle aches, low energy and swollen lymph nodes, as well as a skin rash featuring pus-filled lesions or blisters. In severe cases it can be deadly. 
 

When did the mpox outbreak start and where is it spreading? Which countries have the highest risk of mpox?

The current mpox outbreak started in the DRC in January 2023 and is now DRC’s worst-ever mpox outbreak, with 27,000 cases and more than 1,100 deaths, many of them among children. The outbreak is being caused by two subgroups of the clade I strain of mpox: clade Ia and Ib. 

Rwanda, Uganda, Burundi and Kenya have now also reported cases—countries that have never before reported mpox infections. In mid-August 2024, Sweden reported the first case of the clade Ib form of mpox outside Africa.

A multi-country outbreak of mpox clade II led to the declaration of an international health emergency in 2022. It spread rapidly via sexual contact and in many countries where the virus had not been seen before. The emergency was declared to be over in May 2023 following a sustained global decline in cases.
 

What does mpox look like? And how does it spread?

Mpox spreads from person to person through close physical contact. There is no evidence that it spreads easily through the air. The current clade Ib strain of the virus is causing heightened alarm in part because of the speed with which it has spread. The reasons for this are not yet clear and the WHO has emphasised that additional research is needed to better understand the recent increase in mpox cases.
 

Is there a cure for mpox? 

There is currently no cure for mpox, but scientists and global health organisations are working on mpox treatments and diagnostics. There are two mpox vaccines currently licensed for emergency use in DRC—one made by Denmark’s Bavarian Nordic and the other by Japan’s KM Biologics—that can help reduce the risk of getting infected. Vaccination of vulnerable populations has not yet begun but regionally led efforts are underway to secure doses and initiate a vaccination campaign.

As part of international scientific efforts to advance work on mpox vaccines, CEPI is funding two studies of Bavarian Nordic’s MVA-BN® vaccine—the first to assess how well it works in children, and the second to evaluate whether post-exposure vaccination could reduce the risk of secondary mpox cases or reduce the severity of illness after infection. CEPI is also supporting the development of a next-generation mRNA-based mpox vaccine that is in early clinical development by the German pharmaceutical company BioNTech.