US Reengagement with Gavi Alliance Aims to Bolster Ebola Vaccine Access

Ebola virus disease, caused by several species of Ebolavirus, presents with severe, often fatal, haemorrhagic fever. Transmission occurs through direct contact with blood, bodily fluids, and tissues of infected individuals or animals. The incubation period typically ranges from 2 to 21 days. Clinical manifestations include fever, fatigue, muscle pain, headache, and sore throat, followed by vomiting, diarrhoea, rash, impaired kidney and liver function, and in some cases, internal and external bleeding. Case fatality rates have varied significantly across outbreaks, historically ranging from 25% to 90%.¹

The primary species responsible for the majority of human outbreaks is Zaire ebolavirus, which has been associated with the largest and most complex epidemics. Other species, such as Sudan ebolavirus and Bundibugyo ebolavirus, also cause severe disease but have been less frequently implicated in widespread outbreaks. The natural reservoir for Ebolaviruses is believed to be fruit bats, which can transmit the virus to other animals, including non-human primates and duikers, through contact with their faeces or saliva. Humans typically contract the virus through contact with infected animals or through human-to-human transmission within communities and healthcare settings. Unsafe burial practices, where mourners have direct contact with the deceased, have also been identified as significant drivers of transmission during outbreaks. The rapid progression of symptoms and high transmissibility underscore the urgent need for effective preventive and control measures.

Vaccination represents a primary public health intervention for controlling Ebola outbreaks. The rVSV-ZEBOV vaccine (Ervebo) received its first regulatory approval in 2019 and has demonstrated substantial efficacy in preventing EVD. During the 2018-2020 Ebola outbreak in the Democratic Republic of Congo, ring vaccination strategies employing rVSV-ZEBOV were instrumental in containing the spread of the virus.² The vaccine is a single-dose, live, attenuated recombinant vesicular stomatitis virus (VSV) that expresses a glycoprotein from the Zaire ebolavirus.³ This glycoprotein is critical for the virus's entry into host cells and is the primary target for neutralising antibodies. By expressing this glycoprotein, the rVSV-ZEBOV vaccine elicits a robust immune response, including both humoral and cellular immunity, providing protection against subsequent exposure to Zaire ebolavirus. The ring vaccination strategy involves identifying confirmed EVD cases and then vaccinating their contacts and contacts of contacts, creating a protective "ring" around the infected individual to prevent further transmission. This targeted approach maximises vaccine impact in outbreak settings where widespread vaccination may not be feasible or necessary.

Global Vaccine Access and Policy Shift

Gavi, the Vaccine Alliance, is a public-private global health partnership committed to increasing access to immunisation in low-income countries. Since its inception in 2000, Gavi has supported the vaccination of over 1 billion children, preventing more than 17 million future deaths.⁴ Its operational model involves pooling demand and negotiating prices with vaccine manufacturers, thereby making vaccines more affordable and accessible for eligible countries. Gavi's portfolio includes support for routine immunisation, outbreak response, and the establishment of vaccine stockpiles.⁵ These stockpiles are crucial for rapid deployment during sudden outbreaks, ensuring that vaccines are available immediately when needed most. Gavi also works to strengthen health systems in recipient countries, addressing barriers to vaccination such as inadequate cold chain infrastructure, insufficient healthcare personnel, and logistical challenges in reaching remote populations. This holistic approach ensures that vaccines not only arrive in countries but also reach the individuals who need them.

The US government's stated intention to reengage with Gavi signifies a renewed commitment to multilateral approaches in global health security. This reengagement is expected to provide additional financial and political support to Gavi's initiatives, including those specifically targeting Ebola. Increased US involvement could facilitate broader procurement and distribution of existing Ebola vaccines, as well as accelerate research and development for next-generation EVD countermeasures. The policy shift aims to enhance preparedness and response capabilities in regions prone to Ebola outbreaks, thereby mitigating the risk of international spread.⁶ This renewed partnership is particularly significant for populations in sub-Saharan Africa, where the majority of Ebola outbreaks have occurred. These populations often face significant challenges in accessing essential healthcare services and vaccines due to limited resources, geographical barriers, and ongoing conflicts.

The implications of this reengagement extend to the operational capacity of Gavi to respond to emerging infectious disease threats. By bolstering the alliance's resources, the US aims to strengthen the global health architecture against future pandemics. This includes supporting cold chain infrastructure, training healthcare workers, and improving surveillance systems in vulnerable populations. The focus on Ebola is particularly pertinent given the recurrent nature of outbreaks and the potential for rapid escalation in areas with fragile health systems.⁷ Furthermore, the reengagement can help address equity gaps in vaccine access, ensuring that life-saving interventions reach the most vulnerable populations, regardless of their country's economic status. This collaborative effort is essential for building resilient health systems capable of preventing, detecting, and responding to infectious disease threats effectively.