Will vaccines help stop the mpox outbreak in Africa?
The mpox outbreak unfolding in Africa has been declared a public health emergency. Could vaccines help stop the spread?
- 16 August 2024
- 6 min read
- by T V Padma , James Fulker
Red alert on mpox
This week, the World Health Organization declared the ongoing mpox outbreak in Africa a public health emergency of international concern, while the Africa Centres for Disease Control (Africa CDC) declared it a Public Health Emergency of Continental Security. A new clade of the virus developed and began to spread last year. So far this year, more than 17,000 suspected cases have caused 517 deaths across the continent, outstripping 2023's toll.
Gavi has been monitoring mpox with concern since 2022, as it has travelled and changed. In June this year, the Board approved a number of response measures that include:
- Establishing a global stockpile of mpox vaccines
- Supporting outbreak response in the Democratic Republic of the Congo and its neighbours, including by facilitating donations
- Supporting vital research to inform future vaccination strategies
Alarming rise in cases
While smallpox was eradicated in 1980, mpox continues to occur in countries of central and west Africa, according to the WHO. Since May 2022, cases have also been reported from countries without previously documented mpox transmission outside the African region.
“We are seeing an increase in terms of outbreaks in Africa. We are moving from almost two outbreaks per week to three new outbreaks per week,” said Africa CDC Director-General Jean Kaseya.
Compared to a 69% rise in infections in 2023 over 2022, there has been a whopping 160% rise in 2024 compared to 2023. In 2024, there has also been a 19% increase in the number of cases and deaths compared to 2023. Currently, 12 countries have reported cases: DRC, South Africa, Kenya, Rwanda, Uganda, Burundi, CAR, the Republic of the Congo, Cameroon, Nigeria, Côte d’Ivoire and Liberia. Sweden has also reported the first case of the new Clade 1b variant outside of Africa.
According to Africa CDC data, since the beginning of 2024, more than 17,000 cases (2,863 confirmed) and 517 deaths of mpox have been reported across the continent.
“What is critical to know is that in the past five days, we have six new countries that are affected,” Kaseya said. The Democratic Republic of the Congo (DRC) continues to be the epicentre of the outbreak, accounting for 96.3% of all cases and 97% of all deaths reported in 2024.
Mpox epidemiology
Mpox is a zoonotic disease transmitted from animals to humans, with cases often found close to tropical rainforests where there are animals such as squirrels, different species of monkeys and Gambian pouched rats that carry the virus, says WHO.
The new clade
The mpox virus has two main types called Clade I and Clade II (a clade is a grouping of organisms, in this case, viruses, emergent from a common ancestor).
Clade I, endemic to central Africa, has killed up to 10% of the people it has infected during previous outbreaks, making it far deadlier than Clade II, the type which spread throughout the world in 2022.
In around September 2023, a new mutation in the Clade I virus created a new variant, which scientists are calling Clade Ib. Clade Ib appears to be spreading mainly through sexual networks.
WHO experts have labelled the spread of the variant “especially concerning” in a statement declaring a public health emergency of international concern (PHEIC) this week.
It can also be spread from humans to humans through contact with body fluids, or the skin lesions that typically appear on infected persons.
A major cause for concern is the sharp rise in infections in youth under 18 years, Kaseya said. About 60% of the cases in DRC are in children under 15, and this rises to more than 70% if one considers those under 18 years.
Vaccine shortage
So, could vaccines help to quell the spread? Africa is currently facing a shortage of supply of mpox vaccines. Africa CDC estimates that currently about 200,000 doses are available compared to a requirement of at least 10 million doses, based on estimates from countries that have prepared vaccination plans.
There are currently two vaccines in use against the disease, both of which have been recommended for use by the WHO Strategic Advisory Group of Experts on Immunization (SAGE).
WHO recommends vaccination only for people who are at risk, for example someone who has been a close contact of someone who has mpox, or someone who belongs to a group at high risk for exposure to mpox, and the organisation does not recommend mass vaccination with these vaccines.
While they have been recommended, they have not yet been fully ‘prequalified’ – a form of licensure – by WHO, which is a lengthy process. An interim measure is an Emergency Use Listing (EUL), which was specifically developed to expedite the availability of unlicensed medical products like vaccines that are needed in public health emergency situations.
The WHO has issued an invitation to manufacturers to submit applications for this listing. Gavi has announced it has accelerated engagement with manufacturers for potential direct procurement of mpox vaccines to support the response to the outbreak, which would follow an Emergency Use Listing by the WHO.
Ramping up the response
As part of the declaration of a Public Health Emergency of International Concern, WHO Regional Director for Africa Dr Matshidiso Moeti said, “Significant efforts are already underway in close collaboration with communities and governments, with our country teams working on the frontlines to help reinforce measures to curb mpox. With the growing spread of the virus, we’re scaling up further through coordinated international action to support countries bring the outbreaks to an end.”
For its part, Gavi has formally declared the mpox situation a regional emergency, meaning funds can be rapidly repurposed for a vaccine response, for example, funding operational costs to support the use of dose donations.
It can also leverage new innovative mechanisms. In June 2024, the Gavi Board approved the final terms of the First Response Fund, the fastest tool in a suite of instruments called the Day Zero Financing Facility, which – in response to a key learning from COVID-19 – seeks to make resources immediately available for a vaccine response to an urgent public health emergency. Gavi could draw on this fund to support both direct procurement of mpox vaccines, as well as country readiness and other aspects of the vaccine response.
A final route to getting vaccines to the African countries that need them is through donated vaccine doses. Several countries in the global north have stockpiles of smallpox vaccines that could be made available to support the mpox effort.
The legal, regulatory and logistical hurdles of donating vaccines are numerous and complex, however this is where experience built up during the COVID-19 pandemic will come in handy. Gavi, through COVAX, has helped coordinate the supply of nearly 1 billion COVID-19 dose donations to 114 countries since 2020. This week it announced that it will offer direct support and share knowledge with countries and partners that wish to do the same with mpox vaccines, while working with them on designing in-country vaccination strategies.
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Vaccine pipeline
Looking further into the future, several more mpox vaccines are in the pipeline, but none are very close to licensure. These include BioNTech’s two candidate vaccines. BioNTech is partnering with the Coalition for Epidemics Preparation Innovations (CEPI) for further development to provide equitable access to the vaccine, if successfully developed and approved, in low- and middle-income countries.
BioNTech reported in Cell in March 2024 that the two candidate mRNA vaccines are a quadrivalent vaccine BNT166a encoding three mpox virus antigens, and a trivalent vaccine BNT166c with only two of these antigens. BioNTech scientists report that both candidates induced robust T cell responses and antibodies in mice.
The priority for now, however, is to expedite the roll-out of the vaccines we have. As Kaseya warned: “We are losing the youth in Africa.”
