Ebola vac­cine may be ‘100% ef­fec­tive’: WHO

Vac­cine could be­come avail­able in 2018

Kuwait Times - - HEALTH -


A pro­to­type vac­cine for Ebola may be “up to 100 per­cent ef­fec­tive” in pro­tect­ing against the deadly virus, the World Health Or­ga­ni­za­tion (WHO) said yesterday. If all goes well, the vac­cine could be­come avail­able in 2018 un­der a fast-track ap­proval process, it said. In a ma­jor clin­i­cal trial, nearly 6,000 peo­ple in Guinea were given the test vac­cine last year, at the tail end of a lethal epi­demic of Ebola.

Not one of the 6,000 con­tracted the dis­ease. But in a con­trol group of vol­un­teers that did not re­ceive the vac­cine, 23 Ebola cases oc­curred, re­searchers re­ported in The Lancet med­i­cal journal. “If we com­pare zero to 23, this strongly sug­gests that the vac­cine is very ef­fec­tive, that it could be up to 100 per­cent ef­fec­tive,” Marie-Paule Kieny, WHO’s as­sis­tant di­rec­tor-gen­eral and lead au­thor of the study, told AFP.

Her team of three dozen re­searchers cal­cu­lated a 90-per­cent like­li­hood dur­ing a fullfledged epi­demic that the vac­cine, dubbed rVSV-ZEBOV, would work in more than 80 per­cent of cases. “Af­ter 40 years, we ap­pear to now have an ef­fec­tive vac­cine for Ebola virus dis­ease to build upon,” Thomas Geis­bert, a sci­en­tist at Galve­ston Na­tional Lab­o­ra­tory in Texas who did not take part in the study, wrote in a com­men­tary, also in The Lancet.

‘Com­pas­sion­ate use’

First iden­ti­fied in 1976 in what is now the Demo­cratic Re­pub­lic of Congo, the Ebola virus erupted pe­ri­od­i­cally in out­breaks of up to a cou­ple hun­dred cases, mainly across west and east Africa. In early 2014, how­ever, a hand­ful of in­fec­tions in south­ern Guinea mush­roomed rapidly into an epi­demic. Over the next two years, more than 28,000 peo­ple fell ill, mainly in Guinea, Liberia and Sierra Leone. Some 11,300 died.

With a mor­tal­ity rate above 40 per­cent, the dis­ease-one of a cat­e­gory of so-called hem­or­rhagic fevers-has an in­cu­ba­tion pe­riod of up to three weeks. It causes vi­o­lent and painful symp­toms, in­clud­ing vom­it­ing, diar­rhea, or­gan fail­ure and in­ter­nal bleed­ing. The new vac­cine was ini­tially de­vel­oped in Canada by pub­lic health au­thor­i­ties be­fore being taken over by phar­ma­ceu­ti­cal giant Merck.

It is slated to be submitted by Merck to health au­thor­i­ties in the United States and Europe some­time next year un­der a fast­track ap­proval process. “We may have a vac­cine which is reg­is­tered in 2018,” Kieny told jour­nal­ists at a press con­fer­ence Thurs­day, not­ing that the stan­dard ap­proval process for a new drug takes a decade, if not more. In the mean­time, Merck has com­mit­ted to en­sur­ing that 300,000 doses of the vac­cine are avail­able for emer­gen­cies un­der a pro­to­col called “com­pas­sion­ate use”. “They will be able to pro­duce a mil­lion in very short pe­riod of time,” Kieny noted.

Unan­swered ques­tions

There are still ques­tions to be re­solved con­cern­ing the vac­cine, in­clud­ing side ef­fects. Ini­tial tests last year did not in­clude chil­dren, while the most re­cent tri­als covered those over six years old. Of the more than 6,000 peo­ple in­jected with the Ebola vac­cine only two showed se­ri­ous ad­verse ef­fects, the study re­ported. Both re­cov­ered fully. But it is still un­known if the vac­cine is safe for chil­dren six and un­der, preg­nant women, or peo­ple with the AIDS virus-all groups that were ex­cluded from the most re­cent tri­als.

An­other un­known is how long in­noc­u­la­tion lasts. “With the Cana­dian Merck vac­cine, you have a pro­tec­tion very early af­ter vac­ci­na­tion, but we don’t know if it will last af­ter six months,” Kieny said. Other Ebola vac­cines un­der de­vel­op­ment-some of which have been tested in hu­mans-could prove more ef­fec­tive over a longer pe­riod.

Bri­tish firm Glax­osmithk­line and John­son & John­son, based in the United States, each have ex­per­i­men­tal prod­ucts in the pipe­line. China and Rus­sia have also de­vel­oped vac­cines, with the Rus­sian one hav­ing just fin­ished the sec­ond phase of three-step clin­i­cal tri­als. Some of these vac­cines re­quire two doses three weeks apart, and may con­fer a longer im­mu­nity. “That might be better suited to im­mu­nize health work­ers in ad­vance of an out­break,” Kieny said. Health of­fi­cials also point to the fact that other strains of the virus-in­clud­ing one in Su­dan­will re­quire the de­vel­op­ment of sep­a­rate vac­cines. — AFP

CONAKRY: This file photo taken on March 10, 2015 shows a woman get­ting vac­ci­nated at a health cen­ter in Conakry dur­ing the first clin­i­cal tri­als of the VSV-EBOV vac­cine against the Ebola virus. —AFP

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