In September 2022, Uganda declared the first Ebola outbreak in a decade, caused by Sudan ebolavirus (SUDV). Soon after, two separate outbreaks of Marburg virus were declared in Equatorial Guinea and Tanzania and more recently in Rwanda. 

The disease, named after the Ebola River Valley which is the site of its first outbreak in 1976, Ebola virus is a filovirus that causes haemorrhagic fever and is associated with a high mortality rate. 

There are five well-known species in the genus: Zaire ebolavirus, Sudan ebolavirus, Taï Forest ebolavirus (previously named Côte d’Ivoire), Reston ebolavirus, and Bundibugyo ebolavirus, discovered in 2007. 

Sudan ebolavirus survives in wild animals and humans are frequently infected via animal exposure.  

Long-standing concern

Marburg virus (MARV), another member of the filovirus family, has been a major concern since 1967, causing many outbreaks in sub-Saharan Africa, with two major ones in 1998 and 2004.

There is a single species of Marburg – Marburg Marburgvirus. Human infection with MARV usually results from prolonged exposure to infected Rousettus bat colonies, and similar to EBOV and SUDV, its infection causes severe haemorrhagic fever, organ failure and death. 

Although less frequent than Zaire ebolavirus (EBOV), SUDV infection displays similar symptoms as EBOV, with a mortality rate of 55%. Marburg virus disease can have a fatality ratio of up to 88%.

Control is primarily achieved through community engagement surveillance, contact tracing and case management, as well as risk communication. 

The most recent outbreak in Rwanda (October 2024) highlights the serious public health threat that transmission of a filovirus represents. 

A number of vaccines against ebolavirus (originally called Zaire ebolavirus) have been licensed for use. 

These vaccines include viral vector platform technologies, some of which demonstrated efficacy during the West Africa 2013-2015 outbreak and others which were licensed by the ‘animal rule’.

There are no licensed vaccines against Sudan Ebolavirus or Marburg virus. 

However, the ChAdOx1 platform technology, which was successfully used during the covid-19 pandemic, represents a feasible solution to generating a vaccine against filoviruses. 

Effective platform

When compared to other technologies, the ChAdOx1 platform responds well to high demand, high volume, low cost, global storage conditions and the need for fast deployment in a pandemic situation. 

This platform is highly immunogenic, eliciting an immune response both cell mediated, specifically CD8 + T cell response, and humoral immune response. 

Other equally important advantages are:

• Speed;
• Ease of manufacture and scale-up;
• Ease of deployment;
• Technology transfer to other manufacturers to ensure worldwide supply;
• Cost of goods. 

The ChAdOx1 nCoV-19 vaccine was approved or granted emergency authorisation in approximately 100 countries, and had over 20 partners collaborating on its manufacture. 

This resulted in more than 3 billion doses released for supply in more than 180 countries and an estimated > 6 million lives saved in 2021 alone.

During the filovirus outbreaks in 2022 and 2023, candidate filovirus vaccines designed and progressed by Professor Lambe’s team at the University of Oxford were shortlisted by the WHO Technical Advisory Group on candidate vaccine prioritization (TAG-CVP) for inclusion in ring vaccination protocols to combat the outbreaks. 

Prof Lambe and team, based in the Pandemic Sciences Institute and Oxford Vaccine Group, worked with partners to rapidly scale vaccine production generating more than 300,000 doses of the vaccine. 

They filled 40,000 doses less than 80 days from receiving the starting material for the candidate vaccine against the Sudan ebolavirus outbreak strain. Global partnerships, working closely with the WHO and the relevant ministries of health, offers real-world solutions to the continued threat of the next pandemic.

The Covid-19 pandemic demonstrated that a more rapid vaccine development and deployment pathway is needed and given that experience, we are in a unique position to make real change and to better prepare for the next outbreak.

Opinion articles do not necessarily reflect the views of Science Arena or Hospital Israelita Albert Einstein.

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