After Merck success, work goes on with other Ebola vaccines

By Ben Hirschler

LONDON, July 31 (Reuters) - Scientists and drug companies will continue to research the potential of alternative Ebola vaccines, despite a shot from Merck (Other OTC: MKGAF - news) and NewLink Genetics (Berlin: 4NX.BE - news) proving 100 percent effective in a trial in Guinea.

Experts said on Friday different kinds of vaccines were needed that might be better suited for different population groups.

Because Merck's VSV-ZEBOV is a live, or replicating, vaccine, there were initial worries about its safety. In the event, it proved about as safe as a flu vaccine, said University of Reading virologist Ben Neuman, but it was still not given to children or pregnant women.

Replicating vaccines have the advantage of requiring only one dose, making them suitable for emergency use. But non-replicating vaccines, which may need two injections, could be longer-lasting and better suited to protecting people outside an epidemic.

"There is a place for all of these different modes and it's important that development work on other vaccines continues," Rebecca Grais, director of research at Medecins Sans Frontieres (MSF) Epicentre, told Reuters.

"It's also important to have multiple manufacturers in order to ensure competition."

MSF was one of the organisations behind the successful clinical trial with Merck's vaccine, which the World Health Organization said had brought the world to the verge of being able to protect humans against Ebola.

GlaxoSmithKline (Other OTC: GLAXF - news) applauded its rival's success but said it would persevere with development of its alternative non-live vaccine.

"We believe that it is important that the international community continues to support the development of more than one vaccine for the control of Ebola including those that might be more suitable for vaccination of pregnant women, infant children and the immunocompromised," it said in a statement.

GSK hopes also hopes to test its vaccine in Guinea, although WHO vaccine expert Marie Paule Kieny said this might not be possible, given the dwindling number of Ebola cases.

Johnson & Johnson (NYSE: JNJ - news) , which is developing a two-injection vaccine in partnership with Bavarian Nordic (Copenhagen: BAVA.CO - news) , said it remained committed to the programme and hoped to start a trial in Sierra Leone in the coming weeks.

A number of other groups are at an earlier stage of research, including a team from the University of Texas working on an inhaled vaccine.

Adrian Hill, director of the Jenner Institute at the University of Oxford, said the success of Merck's vaccine suggested other products in mid-stage trials should also prove effective.

Although these alternatives may not be tested during the current epidemic, they could still be licensed and readied for use in future outbreaks based on human immune response results and data from non-human primate experiments. (Additional reporting by Tom Miles in Geneva; Editing by Elaine Hardcastle)