What Matters in Global Health - 161

WHO Pre-Qualifies First Mpox Vaccine and Recommends Single Dose for Children

The World Health Organization (WHO) has taken a major step in global health by prequalifying Bavarian Nordic’s MVA-BN vaccine , the first mpox vaccine approved for global use. This achievement is vital in addressing the rising mpox cases, especially in Africa. WHO's prequalification allows this vaccine to be utilised in outbreak situations, ensuring timely intervention in regions that need it the most.

The WHO’s prequalification (PQ ) and Emergency Use Listing (EUL ) frameworks evaluate medical products’ safety, quality, and efficacy, ensuring global distribution in emergency settings. According to the WHO, "PQ is based on the review of a full set of quality, safety, and efficacy data on medical products".

This decision follows the ongoing global mpox outbreak, with more than 103,000 cases confirmed across 120 countries since 2022. In 2024 alone, there have been over 25,000 cases and 723 deaths across 14 African countries, making swift vaccine distribution essential.

One significant recommendation is the use of a single dose in supply-constrained situations. Typically given as a two-dose vaccine, WHO now recommends a single dose in outbreaks where supplies are limited. Data indicates that one dose provides 76% effectiveness compared to 82% with two doses. This flexibility broadens access in high-risk areas.

Another key development is the approval of "off-label" use for children. Although the vaccine is registered for adults aged 18 and above, WHO’s decision reflects the high number of paediatric cases in regions like the Democratic Republic of the Congo (DRC). Dr Ana-Maria Restrepo of WHO confirmed that studies demonstrate the vaccine’s effectiveness in children.

Additionally, WHO recommends using the vaccine "off-label" for pregnant women and immunocompromised individuals in outbreak settings, underscoring the need to prioritise vulnerable groups.

Despite these advancements, equitable access remains a challenge. WHO Director-General Dr Tedros Adhanom Ghebreyesus highlighted the urgent need for ramped-up vaccine procurement and distribution: “We now need urgent scale-up in procurement, donations, and rollout to ensure equitable access to vaccines where they are needed most". Disproportionately affected by the outbreak, Africa remains a priority for vaccine distribution.

Bavarian Nordic , the vaccine's manufacturer, is working to meet demand by producing two million doses by the end of 2024, with plans to increase production to 13 million doses by the end of 2025. Additionally, the company has requested the European Medicines Agency to extend approval for adolescents aged 12-17. Efforts are also underway to evaluate the vaccine's safety in younger children aged 2-12 through collaborations with partners like the Coalition for Epidemic Preparedness Innovations (CEPI).

Targeting Post-Exposure Prophylaxis for Ebola Virus Disease

Ebola virus disease (EVD) remains one of the deadliest infections, with fatality rates exceeding 50%. Transmitted via close human contact, EVD outbreaks have historically devastated regions like West Africa and the Democratic Republic of the Congo (DRC). A new article in The Lancet Global Health discusses targeted post-exposure prophylaxis (PEP) to improve outbreak control, focusing on those at high risk of developing EVD.?

Monoclonal antibodies, vaccines, and antivirals are considered leading PEP candidates. Monoclonal antibodies, in particular, have shown promise in reducing mortality for those with confirmed cases of EVD. These antibodies work quickly by directly attacking the virus, making them an ideal PEP option for people at high risk of infection, such as healthcare workers and close family members of patients. “This intervention could save lives, halt viral transmission, and ultimately help curtail outbreak propagation,” the authors suggest.

Monoclonal antibodies, such as mAb114 and REGN-EB3 , are approved for treating symptomatic EVD and are administered primarily to high-risk individuals. These antibodies have been used successfully in cases where contacts were exposed to the virus. For example, during an outbreak in the DRC, 23 high-risk individuals received monoclonal antibodies and were symptom-free after 14 days. This data suggests that monoclonal antibodies may offer a crucial protective measure for those exposed.

However, using monoclonal antibodies as PEP is still unproven in large-scale clinical trials. The forthcoming EBO-PEP trial aims to compare the effectiveness of monoclonal antibodies against the current ring vaccination approach used to manage outbreaks.

The rVSV-ZEBOV vaccine , currently used in ring vaccination strategies, has been effective in preventing disease spread but has limitations when used post-exposure. “The delayed antibody response raises important concerns regarding the potential for vaccines alone as PEP,” as it may take days for immunity to develop. Combining vaccines with monoclonal antibodies may offer faster, more effective protection in future outbreaks.

Children Show Up in Droves for Gaza’s Dangerous Polio Campaign

The Gaza Strip is witnessing a rare ray of hope amidst the ongoing war, as a massive polio vaccination campaign aims to immunise 150,000 children in its northern region. This 12-day campaign , led by the Palestinian Ministry of Health in collaboration with the United Nations Relief and Works Agency (UNRWA), the World Health Organization (WHO), and UNICEF, has succeeded in central and southern Gaza. However, challenges remain as the virus spreads in the conflict-ridden area.

A staggering 640,000 children under the age of 10 are being targeted, with at least 90% needing vaccination to halt the spread of poliovirus. The stakes are high, as children under eight are particularly vulnerable to the circulating strain of vaccine-derived poliovirus type 2. Philippe Lazzarini, head of UNRWA, warned, “This is a race against time,” stressing the urgency of reaching every child.

The outbreak, first detected in July, may have been circulating silently since September 2023. The virus thrives in Gaza’s unsanitary conditions, with open sewage running through overcrowded camps for the displaced. Adele Khodr, UNICEF’s regional director for the Middle East and North Africa, describes the campaign as “among the most dangerous and difficult vaccination campaigns on the planet.” Th e campaign faces immense obstacles.

The campaign's success is largely due to the “humanitarian pauses” agreed upon by Israeli authorities, allowing vaccinations to proceed in designated safe zones. Despite these zones, some teams have ventured into more dangerous areas to reach children. Hamid Jafari of the Global Polio Eradication Initiative praised the humanitarian pause as “the first success and most important one,” adding that it has built confidence among health workers and the community.

During the first phase in central Gaza, more than 195,000 children were vaccinated—well above the expected 157,000. In southern Gaza, where fighting has been more intense, nearly 270,000 children have been immunised. Yet the campaign’s success remains uncertain, with concerns that some children may have been missed due to the ongoing conflict.

The poliovirus outbreak poses a threat not only to Gaza but also to surrounding regions, including Israel, Jordan, and Egypt. WHO Deputy Director Mike Ryan acknowledged that the global attention is due to the risk of the virus spreading beyond Gaza’s borders, stating, “The world only wakes up when the threat is beyond national borders”.