A Review of Ebola Vaccine Candidates

Colorized scanning electron micrograph of a single filamentous Ebola virus particle. Credit: NIAID

In a new article published in The Lancet, experts review the current field of Ebola vaccine candidates and clinical trials and highlight key gaps in knowledge that need to be addressed by future research.

The authors note that 36 trials of Ebola vaccine candidates have been completed and another 14 are active, according to clinicaltrials.gov. The rVSV-ZEBOV experimental vaccine, which has been deployed in the Democratic Republic of the Congo, is the only candidate with some clinical efficacy data, which were obtained in a clinical trial in Guinea conducted during the 2014-2016 Ebola outbreak in Guinea.

Study volunteer receives an inoculation at Redemption Hospital in Monrovia, Liberia on the opening day of PREVAC, a Phase 2 Ebola vaccine trial in West Africa. Credit: NIAID

After reviewing the status of four additional vaccine candidates under study (Ad26.ZEBOV, MVA-BN-Filo, chAd3-EBO-Z, and the GamEvac-Combi vaccine), the authors highlight areas where more research is required. Specifically, they note the need for more data in pregnant women, children and immunocompromised populations, including people infected with HIV and the elderly. Additionally, they say more research is needed on the durability and rapidity of immune responses generated by various vaccine approaches.

The experts also call for studies to identify reliable correlates of protection as well as large-scale trials to fully evaluate the safety and efficacy of experimental vaccines.

Read more: Prevention of Ebola virus disease through vaccination: where we are in 2018. The Lancet DOI: 10.1016/S0140-6736(18)31710-0 (2018).

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