The global Ebola emergency may be officially over, but Johnson & Johnson ($JNJ) is pressing on with its program, reporting Tuesday that 100% of participants in a Phase I trial were still producing Ebola antibodies 8 months after vaccination.
J&J and Denmark’s Bavarian Nordic are working on a “prime-boost” Ebola vaccine regimen. According to a J&J statement, the study participants were randomized into four groups, and received either J&J’s AdVac candidate or Bavarian Nordic’s MVA-BN jab as a “prime” dose, followed by the other candidate or placebo as a booster. The booster was given 28 or 56 days later. A fifth open-label group got AdVac followed by MVA-BN 14 days later. In addition to proving safety and immunogenicity, the study’s goal was to measure the durability of the immune response.
The combination of J&J’s jab as a primer and Bavarian Nordic’s as a booster was the most effective. Of the volunteers who received this combo, 97% had produced Ebola antibodies and more than half had generated Ebola-specific T cells four weeks after getting the priming dose, J&J said. Three weeks after the group got the booster shot, all of them were making Ebola antibodies. Depending on when the booster was given, 79% to 100% of patients had developed Ebola-specific T cells after three weeks.
“[T]hese data indicate that the vaccine regimen can induce two types of immune response--antibody-based and cellular--which together may have the potential to confer long-term protection against Ebola,” said Yves Levy, Inserm CEO, in the statement. Inserm is one of the collaborators in the public-private partnership that conducted the trial.
The study was published in the Journal of the American Medical Association and took place in the U.K. It is also the first set of clinical results for the "prime-boost" jab. It is currently in 10 clinical studies in the U.S., Europe and Africa.
The end of the most recent Ebola epidemic means J&J won’t get the chance to test the real-world efficacy of its vaccine until the next outbreak. J&J’s science chief Paul Stoffels recognizes the risk of flare-ups and future outbreaks thanks to the Ebolavirus’ ability to persist in Ebola survivors’ bodily fluids. And while Merck ($MRK) and partner NewLink ($NLNK) are far ahead, with plans to submit their Ebola candidate for approval next year, NIAID Director Anthony Fauci told Bloomberg that “there is always room for more than one vaccine.”
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Image: Volunteer Idrissa Kamara receives the first dose of the prime-boost vaccine regimen at a health clinic in Sierra Leone (2015)--Courtesy of Johnson & Johnson