EbolaEffective Ebola vaccine may be available sooner rather than later: Scientists

Scientists have said they were cautiously optimistic that an effective Ebola vaccine may be available sooner rather than later after trials of an experimental jab found that it gave monkeys long-term protection from the disease.

U.S. government researchers said that animals which received a first shot of the vaccine and a booster two months later were immune to the infection for ten months. If additional trials show that the vaccine works safely in humans, it could be used to protect health workers and contain future outbreaks by immunizing villagers living next to affected areas.

The Guardian notes that the findings will encourage scientists who have just begun human trials of an Ebola vaccine in the hope of preventing another outbreak.

The disease, which was discovered in Guinea in March, has spread rapidly through Guinea, Liberia, Sierra Leone, and Nigeria – with a few cases reported late last week in Congo and Cameroon — claiming more than 2,000 lives and infecting about 7,000.

Scientists with the World Health Organization (WHO) last week warned that the total death toll in West African could reach 20,000 before the virus is brought under control. If the disease spreads to other parts of the continent – as the cases in Congo and Cameroon signal – the death toll would be much higher.

The Guardian reports that researchers led by Nancy Sullivan at the U.S National Institutes of Health (NIH) in Maryland tested two different vaccines on macaques. The first was based on a harmless monkey virus which had been modified to carry a protein from the Zaire strain of Ebola, responsible for the latest outbreak. A single shot of the vaccine protected the animals from the virus for several weeks. The same vaccine, developed by the U.S. NIH and GlaxoSmithKline, has just gone into human clinical trials in the United Kingdom, Mali, and the Gambia.

The U.S. researchers then tested a second vaccine based on a modified cowpox virus. Monkeys which received the vaccine as a booster two months after the first vaccine were protected against lethal doses of Ebola for a full ten months, according to a report in Nature Medicine.

The Guardian understands that U.K. researchers are keen to include the booster jab in future human trials.

Jonathan Ball, a molecular virologist at the University of Nottingham, told the newspaper that a single jab that gave even a few weeks of protection could help to contain an Ebola outbreak.

“This is important as it would keep the dosing regimen simple and could still provide good protection in the sort of outbreak that we are seeing in western Africa at the moment,” he said. “For longer-term protection to prevent future outbreaks one could envisage using the combination, the so-called prime / boost approach.”

Martin Hibberd, professor of emerging infectious disease at the London School of Hygiene and Tropical Medicine, said the study “gives hope for a successful trial in humans.”

On the ground in Africa, governments are resorting to extreme measures. In Sierra Leone, authorities are ordering people to stay inside their homes for three days later this month as part of an effort to stop the spread of Ebola, a government spokesman said on Saturday. Abdulai Bayraytay said the government was telling people to stay inside their homes on 19, 20 and 21 September. The dates were chosen to give people enough time to stock up on food and other provisions before the ban on movement goes into effect, he said.

— Read more in Daphne A Stanley et al., “Chimpanzee adenovirus vaccine generates acute and durable protective immunity against ebolavirus challenge,” Nature Medicine (7 September 2014) (doi:10.1038/nm.3702)