The world could stop central Africa’s deadly mpox outbreak if it wanted to
The global outbreak of mpox in 2022-23 affected more than 100 countries and grabbed the attention of the scientific community. Research on mpox has intensified since.
The virus behind the outbreak, technically mpox clade IIb, is spread through close physical contact. During the 2022 outbreak it was found in both sperm and vaginal fluid for the first time. This suggests it is sexually transmissible.
Overall, deaths in the 2022 outbreak were very low: 0.1%. However, in people with very weak immune systems – such as those with advanced HIV – deaths were much higher, at around 15%.
The outbreak was curtailed through public health agencies and doctors working in partnership with those most at risk of the disease – sexually active men who have sex with men. Key interventions included ensuring that people knew what signs to look for and how to protect themselves, as well as offering vaccinations.
The more a virus spreads, the greater the likelihood it will mutate. Mutations can allow the virus to be more easily transmissible. This happened with the clade II virus, which branched into two and resulted in the clade IIb global outbreak in 2022. Something very similar has now happened with clade I. Clade I virus caused 14,626 mpox cases and 654 deaths in 2023.
Health inequality is a killer
Doctors in the Democratic Republic of the Congo (DRC) have been battling to contain exponentially rising cases of the more severe clade I mpox, mainly affecting children under 15 and their caregivers.
Mpox can be lethal, especially for children under five years old. The mortality rate for clade I is between 3% and 10%. The variation in mortality rates is due to differences in access to healthcare, such as access to antibiotics, as well as specialist care in hospital and intensive care.
This strain, which has caused significant harm in central African countries such as the DRC, has not attracted the world’s attention in the same way as it has in the west – even though the number of people with the disease was rising year on year. Sadly, it’s very common in global public health for infectious diseases to be neglected unless they affect people in wealthy countries.
Clade I virus is transmitted through close physical contact, respiratory droplets and contact with infected materials like bedding and infected animals. Historically affected countries, like the DRC, have not had access to the vaccine that helped curtail the outbreak in the US, Europe and the UK.
The vaccine – called Jynneos in the US and Imvanex in Europe – has not been made or sold in Africa so far. And at US$100 per dose (£76), it is beyond the affordability of most low- and middle-income countries.
These countries have relied on donations from philanthropic organisations or from governments. However, during the 2022 mpox outbreak, insufficient vaccines were donated to African countries, and local laboratory capacity – needed to test, monitor and respond to cases – was not significantly strengthened. According to experts, wealthier nations, international health agencies and global health donors should have taken the lead in addressing these gaps, but their support fell far short of what was needed.
In 2024, the mpox virus spread very quickly from the Kivu area of the DRC, which is on the eastern border with Uganda, Burundi and Rwanda – and caused over 16,000 new cases and 511 deaths. The rapid spread among heterosexual people who were moving across porous borders with neighbouring countries – and within camps of internally displaced people – prompted scientists to study the virus to see if it had mutated.
The virus has changed significantly enough to warrant being named as a new sub-variant: clade Ib.
These changes may have enabled the rapid spread to several other African countries and the first ever case of clade I virus in Europe (Sweden) in a returning traveller.
Vaccine accessibility
So what does this mean for people in wealthy countries? The risk to the general population is very low. However, travellers to affected countries who mix with affected communities are at risk of contracting mpox and transmitting it to close contacts on return.
We live in an interconnected world, so cases of the new strain are extremely likely to be identified in the coming weeks and months in many countries. But this does not make a global outbreak of clade Ib inevitable. The tools needed to limit the virus from spreading are in use already: community engagement, contact tracing, laboratory surveillance of new cases to monitor spread of clade Ib virus, and vaccination.
Anyone who develops symptoms after being in contact with a returning traveller should isolate and follow national guidance on where to attend for medical care. It’s essential to do this as soon as possible after noticing symptoms because being vaccinated within four days of exposure can limit the likelihood of getting mpox and the severity – and length – of infection.
Mpox causes skin lesions that look like blisters which become filled with pus after a few days – and it can cause ulcers in the mouth and on the genitals and bottom. People diagnosed with mpox should isolate and limit close physical and sexual contact while they have lesions.
Stopping this outbreak is possible if affected countries are equipped with three things: access to free diagnostic tests, laboratory capacity to determine the mpox clade so the extent of the outbreak can be monitored and, most important, equal access to the vaccine.
Millions of doses will be needed to protect people in affected countries. The declaration of a public health emergency of international concern by the World Health Organization will allow better coordination of the international response, such as emergency licensing of the vaccine in all countries and greater capacity to buy and make the vaccine where it is needed most.
Chloe Orkin does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.