Ebola vaccine shows promise in first human trials

A Liberian Ministry of Health worker, dressed in an anti-contamination suit, speaks to Banu, 4, in a holding centre for suspected Ebola patients at Redemption Hospital in Monrovia, Liberia. John MooreShow more

WASHINGTON // Researchers are one step closer to developing an Ebola vaccine, with the first phase of a trial showing promising results.

However, it will be months at the earliest before the vaccine can be used in the field.

The news comes amid the worst ever outbreak of the hemorrhagic fever, which has killed nearly 5,700 people, mostly in West Africa.

Pharmaceutical companies and health agencies are scrambling to fast-track experimental drugs and vaccines that might help stem its spread.

In the first phase of testing, all 20 healthy adults injected with a higher or lower dose of the vaccine developed antibodies needed to fight Ebola, said the National Institutes of Health (NIH), which conducted the study.

“The unprecedented scale of the current Ebola outbreak in West Africa has intensified efforts to develop safe and effective vaccines,” said Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases (NIAID), which is developing the vaccine alongside GlaxoSmithKline.

The vaccines under development “may play a role in bringing this epidemic to an end and undoubtedly will be critically important in preventing future large outbreaks”, he said.

“Based on these positive results from the first human trial of this candidate vaccine, we are continuing our accelerated plan for larger trials to determine if the vaccine is efficacious in preventing Ebola infection,” he said.

But the vaccine is still a long way from being ready for use in the field.

The NIAID is “in active discussions with Liberian officials and other partners about next-stage vaccine testing in West Africa” for efficacy and safety, the NIH said, but no announcement on larger-scale trials was expected before early next year.

There is no licensed treatment or vaccine against the Ebola virus, which is transmitted through bodily fluids and has been fatal in an estimated 70 per cent of cases in the current outbreak.

The volunteers were injected starting in September, and each showed a positive result for Ebola antibodies in blood tests within four weeks.

The 10 volunteers in the higher-dose group developed higher antibody levels, the study showed.

In addition, two of the lower-dose group and seven of the higher-dose group developed a kind of immune cell called CD8 T cells, which are an important part of the body’s response against disease.

“We know from previous studies in non-human primates that CD8 T cells played a crucial role in protecting animals” who got the vaccine and then were exposed to Ebola, said researcher Julie Ledgerwood, the trial’s principal investigator.

None of the volunteers experienced serious side effects within the study period, though two had a brief, mild fever within 24 hours after the injection.

The vaccine uses a modified chimpanzee cold virus to deliver segments of genetic material from the Ebola virus.

The genetic material cannot spread in the body like the virus does, but can still prompt the antibody response.

The version tested at NIH contains material from two species of Ebola –– the Zaire species, responsible for the outbreak in West Africa, and another called Sudan Ebola.

“This work is encouraging and another significant contribution to efforts to tackle the Ebola crisis,” said Dr Jeremy Farrar, director of the Wellcome Trust, a global charitable foundation.

The White House also congratulated the vaccine researchers.

“We congratulate Drs Francis Collins and Tony Fauci and their teams at the National Institutes of Health on the first published results from Phase 1 clinical trials of a promising Ebola vaccine candidate,” the White House said, adding that President Barack Obama would visit the NIH next week.

A second version of the vaccine, aimed at blocking just Zaire Ebola, also began human testing in October at the University of Maryland.

Another experimental vaccine that has shown promising results in primates is the Canadian VSV-EBOV, licensed by US firm NewLink Genetics. It is also in early stages of human testing.

The World Health Organisation said Thursday that the global death toll from the Ebola virus had increased to 5,689 out of a total of 15,935 cases of infection, almost entirely in western Africa.

The new numbers increased the death toll by 230 people in the past week.

The WHO believes that the number of deaths is likely far higher, given the difficulty in collecting comprehensive figures and Ebola’s high fatality rate.

* Agence France-Presse