WHO faces complex vaccine and security questions in Ebola response in Congo

An Ebola outbreak in eastern Democratic Republic of Congo is likely spread over tens of kilometres and poses a high regional risk given its proximity to borders, a World Health Organization (WHO) official said on Thursday.

Four people have tested positive for Ebola in and around Mangina, a town of about 60,000 people in North Kivu province, 100 kilometres from the Ugandan border, the health ministry said.

Another 20 people died from unidentified hemorrhagic fevers in the area, mostly in the second half of July.

News of the outbreak emerged just days after a previous outbreak on the other side of the Central African country that killed 33 people was declared over.

It will be complicated and perhapsimpossible to use a vaccine to tackle thenew Ebola outbreak, WHO'semergency response chief said on Thursday.

Almost20 WHO officials werealready on their way to the epicentre, Peter Salama told Reutersat WHO's headquarters in Geneva.

Officials have not yet confirmed which type of Ebola iscausing the outbreak. That information, expected within days, iscrucial for the vaccine strategy.

It could be the Zaire, Sudan or Bundibugyo strain of Ebola,Salama said, although the high death rate pointed toward Zaire,the same kind of Ebola that caused Congo's last outbreak, whichwas declared over just last week.

That effort relied heavily on a vaccine by Merck, whichwas given to contacts of Ebola patients, and contacts ofcontacts, to ring-fence the disease and stop it spreading.

"If this [outbreak]turns out to be Ebola Zaire, thencertainly that would bring that option into play," Salama said."If it doesn't we are going to have to look at much more complexoptions, and we may not have any vaccine options."

Merck's vaccine is only effective against the Zaire strain,and is the only vaccine that has gone through Phase 3 efficacytrials, a spokesman for the GAVI global vaccine alliance said.

Another vaccine is being developed by Johnson & Johnsonto protect against multiple related diseases, including
the Sudan strain.

"However it has not been through Phase 3 and it would haveto be deployed as part of a clinical trial," the GAVI spokesmansaid. "While it is promising, we do not yet have reliable dataon its efficacy."

Ring-vaccination depends on tracing all potential Ebolasufferers, which might be impossible in northeast Congo, whereSalama said there were over 100 armed groups. Instead, WHO mightconsider "a more homogenous geographical strategy,"he said.

Security concerns will be assessed on a day-to-day-basis andmay oblige WHO to hold staff back in the cities of Goma andKinshasa until their safety can be assured, he said.

Armoured personnel carriers and support from United Nationspeacekeepers may be needed, making it very difficult to deploythe kind of far-reaching contact tracing used in the previousoutbreak.

WHO dealt with an outbreak in the same area around a decadeago, "where we had to negotiate with many armed factions," Salama said.

"So there is experience in the organization. That's not tosay this is going to be simple."