Scientists are making “remarkable progress” in developing a safe, effective Ebola vaccine, says Wits University’s Professor Helen Rees.
She should know. Rees chaired a high-level World Health Organisation (WHO) meeting in Geneva last week, where the progress of three potential – or “candidate” – vaccines was discussed.
Also in attendance were health ministers, ambassadors and scientists. Rees, a vaccinologist and executive director of the Wits Reproductive Health Institute, told City Press on Thursday that the current Ebola outbreak in west Africa had pushed researchers into a corner.
This is the first time in medical history that it has taken scientists mere months to conduct clinical trials on potential vaccines for a highly infectious disease. It takes an average of 12 years for a drug to move from the testing phase in a laboratory to patient use.
“We had no choice but to move with great speed because the virus was spreading quickly, and a great number of people were being infected and dying in a short space of time,” said Rees.
Potential Ebola vaccines have been in the development stage for decades, but there’s never been any urgency to conduct clinical trials because there has not been a widespread outbreak.
All this changed early last year when Liberia, Sierra Leone and Guinea became the epicentre of an outbreak that has already killed more than 8?400 people.
Rees said despite the race against the clock, scientists would not compromise on quality and safety when creating a vaccine.
“We are aware that there might be concerns about pushing speed, but we can assure the world that we will not compromise on quality,” she said.
“We are going to run [Phase 2 and 3] trials in parallel to ensure we do not waste time.
“We are working with regulatory authorities and data monitoring review boards throughout the process to ensure everything is done to the book.”
The outbreak seems to have tapered off in some areas and the scientists’ haste also relates to making immediate use of available opportunities.
Updated figures from the WHO reveal that the number of confirmed Ebola cases have dropped in Guinea, Liberia and Sierra Leone.
“We have to get into the field very quickly to do these clinical trials, because if there are very few cases of Ebola, it’s going to be difficult to test whether the vaccines work or not,” said Rees.
“We have three candidate vaccines, with more in the pipeline. Two vaccines – one manufactured by GlaxoSmithKline and the other by Merck – have already undergone the first phase of testing, which looks at safety and immunogenicity [to induce immune response].
“Both vaccines have been found to be safe and will now move to the second and third trial.
“Safety and immunogenicity will be tested [in the general population] during the Phase 2 trial and efficacy in the third trial,” she explained.
Rees estimated that this process should take about six months.
The trials are set to take place where they are needed most – in Liberia, Sierra Leone and Guinea.
Three ways in which to get the vaccine
Professor Helen Rees says vaccine researchers are looking at three trial designs – and one of each will be rolled out in Sierra Leone, Guinea and Liberia over the next few weeks.
Liberia: “Vaccines will be tested against each other and against a control [placebo],” she says.
Sierra Leone: “Vaccine doses will be given to frontline workers and there will be no placebo.
“Effectiveness will be determined by looking at whether there are fewer cases of Ebola among workers who are vaccinated earlier, compared with those who are vaccinated later.”
Guinea: Rees says the “ring vaccination” method will be used in Guinea, which was the site of the first reported Ebola case during the current outbreak. In an article in the journal EMBO Molecular Medicine, a team of researchers reported late last year that they believed the origin of the outbreak was a single tree in the village of Meliandou, Guinea. A bat colony living in the tree was blamed for infecting two-year-old Emile Ouamouno in December 2013. The toddler later died.
Ring vaccination involves reacting when a case is reported, then vaccinating whoever has come into contact with the infected person. – Zinhle Mapumulo