West Africa still under Ebola threat

As the world’s attention continues to focus on the threats of the Zika virus, a study published in the Journal of the American Medical Association or JAMA on Tuesday, 19 April sheds light on ongoing efforts to combat the deadly Ebola virus that still threatens countries in West Africa.

The report highlights an ongoing public-private partnership of some of the world’s leading health organizations, which reported the first clinical data for an Ebola vaccine regimen in development at the Janssen Pharmaceutical Companies of Johnson and Johnson.

Partners involved in the clinical program for the Ebola vaccine regimen include the Janssen Pharmaceutical Companies of Johnson and Johnson, the London School of Hygiene and Tropical Medicine, the University of Oxford, Inserm, Bavarian Nordic and Europe’s Innovative Medicines Initiative.

Among the findings, 100 percent of healthy volunteers in the Phase One study achieved an initial antibody response to Ebola, and this response was sustained 8 months following immunization. The findings are significant in light of recent evidence highlighting the persistence of the Ebola virus and ongoing flare-ups of the disease in West Africa, which underscore the need to find a long-lasting vaccine.

The Oxford study provides the first set of data from a total of 10 clinical studies that are being conducted on a parallel track across the U.S., Europe and Africa in support of potential eventual registration for the Ebola vaccine regimen.

The first study of the vaccine regimen in a West African country affected by the recent Ebola outbreak began in Sierra Leone in October 2015. The Ebola outbreak in West Africa began in March 2014 and put the health care systems of Sierra Leone, Liberia and Guinea under tremendous pressure.

More than 28,600 individuals were infected with the virus across the three countries, and more than 11,300 people died– including more than 500 healthcare workers. Unfortunately, flare-ups of the disease continue in the region, most recently in Guinea and Liberia, due to the persistence of the Ebola virus among survivors.

Healthcare and frontline workers are most at risk in an Ebola outbreak and would benefit greatly from a durable vaccine. The Global Public-Private Partnership on the Positive Phase One Data for Ebola Vaccine Regimen publication says the Ebola vaccine regimen produced an antibody response in 100 percent of healthy volunteers that was sustained for eight months following immunization.

But the study says an Ebola vaccine is still urgently needed to address the problem of Ebola persistence in affected countries and to prevent future outbreaks. The Ebola vaccine regimen is being developed by the Janssen Pharmaceutical Companies of Johnson & Johnson, in collaboration with Bavarian Nordic.

According to Johnson and Johnson Chief Scientific Officer Doctor Paul Stoffels, the Ebola crisis in West Africa left a huge human cost, and the region continues to witness flare-ups of the disease. On the basis of such observation, he suggests that the world needs to be far better prepared for the next major outbreak.

“This study suggests that Janssen’s investigational prime-boost vaccine regimen, if approved by regulators, could be an important tool in global strategies to help prevent another Ebola epidemic,” he adds. The Phase One study tested a vaccine regimen containing two components based on “AdVac® technology from Crucell Holland B.V., one of the Janssen Pharmaceutical Companies, and MVA-BN® technology from Bavarian Nordic A/S.”

Healthy volunteers were said to have been given one vaccine dose to prime their immune system, and then the alternative vaccine to boost their immune response, with the goal of evaluating the duration of immunity.

Prime-boost vaccination is an established approach for the prevention of several infectious diseases. “Recent evidence highlighting the persistence of the Ebola virus in bodily fluids, and the potential for sexual transmission from Ebola survivors, reinforce the importance of finding a robust and durable vaccine for this disease,” said Dr. Matthew Snape of the Oxford Vaccine Group and the study’s lead author.

In the study, most participants were randomized in a blinded fashion to receive either vaccine or placebo, while some individuals were in an open-label group receiving vaccine. Among the randomized participants, 97 percent generated antibodies specific to Ebola four weeks after a priming dose with AdVac; and more than half of AdVac recipients developed Ebola-specific T cells, a key marker of cellular immunity.

Validating the prime-boost concept, these immune responses were enhanced by administration of the MVA-BN booster dose, with 100 percent of participants generating Ebola-specific antibodies at 21 days post-boost, and 79-100 percent showing T cell responses depending on the dosing interval.

Eight months following prime vaccination, 100 percent of individuals in the study maintained Ebola-specific antibodies, while vaccine-induced T cell responses persisted in 77-80 percent of those receiving the AdVac/MVA-BN regimen.

In terms of safety, injection site pain was the most common reported adverse event, and was transient and generally of mild-to-moderate severity. Among randomized participants, fever was reported in 5 percent of AdVac recipients compared to 4.2 percent of those receiving placebo. In the open-label group, 27 percent of participants reported fever.

All episodes of fever were said to resolve within 24 to 48 hours, and no serious vaccine-related adverse events were observed. “Forty years after the discovery of Ebola, the world still needs an approved vaccine for this disease,” said Dr. Peter Piot, Director of London School of Hygiene and Tropical Medicine said.

“A durable prime-boost vaccine could be a vital asset in efforts to proactively protect the general population in countries that are vulnerable to Ebola outbreaks. And in light of the persistent challenges that we are seeing with the Ebola virus, durability has become a particularly important goal for vulnerable populations such as health workers and the families of Ebola survivors,” he said further.-Press release