A pair of randomized, placebo-controlled clinical trials that examined three different Zaire Ebola vaccine strategies in four African nations found that all three prompted an antibody response at 14 days, persisting for 1 year in adults and children. An international group of researchers from the Partnership for Research on Ebola Vaccination (PREVAC) published their findings yesterday in the New England Journal of Medicine.
The trials began in 2017, enrolling 1,400 adults and 1,401 children in Guinea, Liberia, Sierra Leone, and Mali. The vaccine strategies tested were a dose of Johnson & Johnson Ad26.ZEBOV vaccine, with a booster dose of Bavarian Nordic's MVA-BN-Filo given 8 weeks later, two doses of Merck's VSV-EBOV given 8 weeks apart, or one dose of VSV-EBOV followed by a placebo injection 8 weeks later.
Antibody responses were seen by day 14 for all three strategies, which the team said is important, given that the vaccines are given in outbreak situations when rapid production of an antibody response is needed. However, so far, antibody correlates of protection aren't known. None of the volunteers got sick with Ebola during the trial, and researchers weren't able to assess protection.
No safety concerns were identified in the trial.
Second vaccine candidate heads for Uganda
Oxford University's Sudan Ebola vaccine candidate has been shipped to Uganda, just 80 days after the World Health Organization (WHO) declared an outbreak. The shipment includes more than 40,000 doses of the vaccine, which was made by the Serum Institute of India, the university said in a statement.
The Oxford vaccine is based on a modified chimpanzee adenovirus (ChAd1) vector platform. No vaccine has yet to be approved for the Sudan strain.
Ugandan officials and the WHO have prioritized three candidate Sudan Ebola vaccines for clinical trials in the outbreak area, however, a steep decline in cases will make evaluation difficult. The first doses—from the Sabin Vaccine Institute—arrived in the country last week.