UK Begins Human Trials of New Ebola Vaccine
Researcher Alex Sampson holds the experimental Ebola vaccine.
A new vaccine designed to combat Ebola has received approval from the UK regulator to proceed with human trials.
Scientists at the University of Oxford initiated development of the vaccine eight weeks ago following the declaration of a public health emergency on 17 May.
This vaccine is the first among four candidates currently under development to enter clinical trials.
Volunteers are being recruited, with the initial doses anticipated to be administered to healthy adults in the UK within weeks.
The ongoing Ebola epidemic, primarily affecting the Democratic Republic of the Congo, has resulted in 625 deaths and 1,792 laboratory-confirmed cases.
The outbreak is caused by the Bundibugyo species of Ebola, which has been responsible for two previous outbreaks.
The six known species of Ebola are described as "sisters rather than twins" because, despite similarities, each requires distinct treatments and vaccines. Consequently, there are currently no approved drugs or vaccines effective against this species.
The outbreak remains uncontrolled and occurs in a conflict zone with highly mobile populations, underscoring the urgent need for a vaccine to help curb disease transmission.
Details of the Clinical Trial
Dr Katrina Pollock, the chief investigator leading the trial at the University of Oxford, stated to the BBC:
"We're doing phase one (early stage) trials of new vaccines all of the time, precisely to be ready for exactly this kind of outbreak."
The trial will involve 50 healthy adults aged between 18 and 55. Additionally, researchers are collaborating with partners in Uganda to prepare for trials in Africa.
Volunteers will be monitored for one year, though scientists expect to quickly determine whether the vaccine elicits the appropriate immune response or causes any unexpected side effects.
Vaccine Technology and Development
The Oxford team was able to develop the vaccine rapidly by utilizing the same technology that gained prominence during the Covid-19 pandemic and was employed in the Oxford/AstraZeneca Covid vaccine.
This technology uses a common cold virus that infects chimpanzees, which has been genetically modified to be safe for humans.
This modified virus acts as a delivery vehicle, where researchers replace the genetic material inside with a snippet specific to the target virus before introducing it into the body.
In the case of Covid-19, the genetic snippet was from the SARS-CoV-2 virus.
For this Ebola vaccine, the snippet is derived from the Bundibugyo species of Ebola.
The vaccine does not cause infection; instead, the genetic fragment prompts the production of one viral protein from Ebola inside the body.
This is sufficient to activate the immune system to recognize the threat and mount a defensive response.
As a result, the immune system should be primed to respond more effectively if exposed to the actual Ebola virus.
" alt="Graphic showing how an Ebola vaccine would work: Ebola genetic material is placed inside a harmless virus, the modified virus is injected into the body to trigger antibody production, and those antibodies are then ready to fight the Ebola virus if exposure occurs later. It uses illustrations of the Ebola virus, a harmless virus, a syringe, antibodies, and arrows to show each stage of the process. The source is the University of Oxford" />
The vaccine has undergone development and testing in mice and macaque monkeys and is being manufactured to clinical standards by the Serum Institute of India, which has produced and stockpiled approximately 620,000 doses.
Based on these data, the UK's Medicines and Healthcare Products Regulatory Agency has authorized the commencement of human trials.
Vaccine researcher Alex Sampson told the BBC:
"As soon as we heard there was an outbreak, we were able to scale up really, really quickly."
Typically, vaccine research, development, and validation can take up to a decade. However, Sampson emphasized that no safety protocols are being compromised.
"We're doing all the same tests that we would normally do, just we're able to do them in parallel, so it means a lot of teams working in lots of different places around the clock, but we're still doing everything that we would normally,"he added.
Challenges of the Ebola Outbreak and Vaccine Safety
The Oxford Covid vaccine is estimated to have saved six million lives globally in its first year of use, with hundreds of millions of doses administered.
However, its use was limited in some countries due to rare cases of blood clots, affecting up to one in 100,000 recipients.
It is possible that this Ebola vaccine carries a similar risk, although this risk is significantly lower than the threat posed by the Bundibugyo species of Ebola, which has a fatality rate of approximately one-third among those infected.
Dr Pollock stated that severe side effects are "very rare" and that the team has carefully considered the implications of conducting trials on healthy volunteers, ensuring that any risks are clearly communicated.
"I want to stress that the Covid AstraZeneca vaccine was given to millions of people safely,"she added.
Other Ebola Vaccines in Development
There are three additional vaccines being developed targeting the Bundibugyo species of Ebola.
These include a candidate from biotechnology company Moderna, which utilizes mRNA vaccine technology.
The International AIDS Vaccine Initiative and Public Health Vaccines, based in the United States, are developing another vaccine using a technique proven effective against a different Ebola species, though this method has a slower manufacturing process.
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