Merck Ebola vaccine in demand rather than JnJ rival drug

"You do not only vaccinate the people in the household," he said. "You have to consider the household as the case and then vaccinate all the households around the case."

The virus has killed 1,223 of the 1,847 people who have fallen ill, making it the second-worst Ebola outbreak on record.

The new approach aims to protect people in an area where a new Ebola case is reported, irrespective of whether they have a known risk of contact with the patient, as is the case in the current "ring vaccination" approach.

"Somehow we have to catch up with the outbreak and break the transmission chain very quickly," Ilunga said, adding that the new approach had already been used in a few remote villages.

He preferred to use just one vaccine.

"It would perturb the population to be faced with several different types of vaccines and that would muddle the message, and, as you know in complex outbreak response, the message needs to be simple and clear," he said.

Merck's vaccine should be fully licensed as soon as possible to make it easier to use, he said.

"You must realise that all the 100,000 patients have been vaccinated according to a very strict protocol, with compliance, information, consent and so on, so it was not easy. If the vaccine is licensed, it would be easier."

Merck's licensing process is underway but it was unclear how long it would take, he said. Congo's government had not discussed or requested the introduction of J&J's vaccine.

Earlier this month, experts advising the World Health Organization recommended a dramatic expansion of vaccination, as well as the introduction of the J&J treatment and a revised dosage of the Merck vaccine to ensure supplies last longer.