As the Ebola virus continues to spread, and to claim lives – with more than 1 000 suspected cases in the DRC, nine confirmed cases in neighbouring Uganda, and around 250 deaths – three new vaccines are being developed to tackle this latest, rare species, while other drug-makers mull over repurposing Covid treatments, reports the BBC.
The WHO reports that there are 321 confirmed cases in the DRC and 116 suspected cases, with 48 confirmed deaths and more than 240 suspected deaths. Uganda has confirmed nine cases and one death, and one suspected case.
The International Aids Vaccine Initiative (IAVI), which is working on one vaccine, said the outbreak was threatening to be the worst ever.
The University of Oxford and pharma company Moderna are also researching vaccines against the Bundibugyo species.
The Coalition for Epidemic Preparedness Innovations (Cepi), which is providing funding to each group, said “every day counts”.
Experts fear this outbreak could reach the size of the largest ever Ebola outbreak in West Africa in 2014-16. Then, nearly 29 000 people were infected and more than 11 000 died.
Dr Mark Feinberg, head of IAVI, said: “I think this is threatening to be as severe an outbreak as that, if not even worse, and development of a vaccine, and other countermeasures, is clearly a priority.”
It echoes concerns from the medical charity Médecins Sans Frontières (MSF) which said the situation was “deeply alarming” and never before had so many cases been recorded so soon.
Vaccines must be developed for each individual species of Ebola – there are six, but only three are known to cause outbreaks.
There is a vaccine for the most common Zaire species, but this latest outbreak is being caused by the Bundibugyo species, which has only been seen twice before and has no approved vaccine.
IAVI is working on a modified version of the Zaire Ebola vaccine to fight Bundibugyo. The experimental jab has been tested in monkeys where it rapidly trained the immune system and gave close to 100% protection.
Feinberg said at this stage he was optimistic about the potential, but it would take seven to nine months to get the vaccine ready for clinical trials – although they are trying to “accelerate those timelines”.
Meanwhile, Moderna has announced it is using its mRNA technology to work on Bundibugyo, while the University of Oxford has already said it is working on its own vaccine technology, which also saved lives in Covid, to develop a fresh Ebola vaccine.
This should be ready for clinical trials in two to three months.
Joining the race is Merck, which is contemplating using a drug it used in the fight against Covid, reports Reuters.
“Our Covid antiviral pill molnupiravir is a non-specific RNA virus drug, and we’re thinking about how we could use that,” said Eliav Barr, chief medical officer.
The pill, developed with Ridgeback Biotherapeutics and sold under the brand name Lagevrio, was approved for emergency use by the FDA during the pandemic for mild-to-moderate Covid-19 in adults at high risk for severe disease
Molnupiravir has shown some efficacy against Ebola in animal studies and could be useful to prevent Ebola infections in people at high risk, but is not recommended for use during pregnancy.
Why is stopping the outbreak so difficult?
Each vaccine aims to train the body to spot the same structure on the surface of the virus – known as the Bundibugyo glycoprotein. However, each uses a different technology to get there.
IAVI uses a live, but harmless virus that has been engineered so it also has the Ebola glycoprotein. The immune system fights off the harmless virus and learns to fight Ebola in the process.
The mRNA vaccine and the Oxford vaccine both deliver a snippet of genetic code into the body. Once inside it orders the construction of the Bundibugyo glycoprotein, which the body recognises as foreign and starts to attack.
All would mean that the immune system has a head start when it comes to fighting a real Ebola infection.
However, differences in the technologies and the way they train the immune system could affect levels of protection or the number of doses needed. This all needs to be tested in clinical trials.
Cepi is funding the early stages of research. “With the Bundibugyo virus spreading rapidly and no licensed vaccines, every day counts in the race,” said Dr Richard Hatchett, CEO of CEPI.
BBC article – Three Ebola vaccines in development amid growing outbreak fears (Open access)
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