An experimental vaccine against Ebola virus seems to be safe and commands a strong immune response against the virus, according to tests in 20 healthy people in the United States. The results of the phase 1 trial are published in the New England Journal of Medicine.
“All in all, I would say it was a successful phase 1 study,” says Anthony Fauci, director of the US National Institute of Allergy and Infectious Diseases (NIAID) in Bethesda, Maryland, which co-developed the drug with the London-based drug company GlaxoSmithKline (GSK). “The next steps are to move ahead with a larger efficacy trial in West Africa.”
The vaccine is similar to one that is on track to be tested in larger trials in West Africa, which are likely begin early next year. In these phase 2 and phase 3 trials, thousands of people who are at risk of contracting the virus, such as health workers, will receive the vaccine to determine whether it can protect against infection.
The vaccine that has been tested in the United States was made from a cold-causing chimpanzee adenovirus that had been engineered to express proteins from two species of the Ebola virus, known as Zaire and Sudan (after their origins), and that was already available when the trial began in early September. However, the outbreak in West Africa is caused by a strain of virus from the Zaire species, known as Zaire-Guinea. Vaccine developers have agreed that so-called monovalent vaccines that target only the Zaire species should be deployed in West Africa. Safety tests of one such vaccine, also developed by GSK and the NIAID, began in October at several sites, including in Switzerland, the United Kingdom and Mali.