CityPress - - News - ZINHLE MAPUMULO zinhle.mapumulo@city­press.co.za

ci­en­tists have fi­nally de­vel­oped a vac­cine that can pro­tect pa­tients against the deadly Ebola virus.

The World Health Or­gan­i­sa­tion (WHO) an­nounced on Fri­day that one of the can­di­date vac­cines de­vel­oped in a re­search pro­ject by phar­ma­ceu­ti­cal com­pany Merck Sharp & Dohme has been found to of­fer 100% pro­tec­tion against Ebola in hu­mans.

This is great news, but the WHO said more con­clu­sive ev­i­dence was needed to prove the vac­cine’s ca­pac­ity to pro­tect pop­u­la­tions through what is called “herd im­mu­nity”.

Herd im­mu­nity is a form of im­mu­nity that oc­curs when the vac­ci­na­tion of a sig­nif­i­cant por­tion of a pop­u­la­tion pro­vides a mea­sure of pro­tec­tion for oth­ers who have not de­vel­oped im­mu­nity.

Pre­lim­i­nary re­sults of the vac­cine trial were pub­lished in The Lancet on Fri­day.

Dr Mar­garet Chan, WHO di­rec­tor-gen­eral, de­scribed the de­vel­op­ment of the trial, which was con­ducted in Guinea in west Africa, as “ex­tremely promis­ing. The credit goes to the Guinean gov­ern­ment, the peo­ple liv­ing in the com­mu­ni­ties and our part­ners in this pro­ject. An ef­fec­tive vac­cine will be another very im­por­tant tool for both cur­rent and fu­ture Ebola out­breaks.”

Work on the trial be­gan in af­fected com­mu­ni­ties in March. Re­searchers tested the ef­fec­tive­ness and safety of a sin­gle dose of the vac­cine – called VSVEBOV – by us­ing a ring vac­ci­na­tion strat­egy.

Ring vac­ci­na­tion is a process that in­volves health author­i­ties re­act­ing when a case is re­ported, then vac­ci­nat­ing those who have come into con­tact with the in­fected per­son.

More than 4 000 peo­ple who were in close con­tact with al­most 100 Ebola pa­tients, in­clud­ing fam­ily mem­bers, neigh­bours and co-work­ers, vol­un­tar­ily par­tic­i­pated in the trial. The con­fir­ma­tory tri­als, which will test herd im­mu­nity, are ex­pected to be­gin in Guinea soon.

The Guinean na­tional reg­u­la­tory au­thor­ity and ethics re­view com­mit­tee have al­ready ap­proved the con­tin­u­a­tion of the trial.

Dr Sakoba Keita, Guinea’s na­tional co­or­di­na­tor for the Ebola re­sponse, said: “This is Guinea’s gift to west Africa and the world.”

Ex­plain­ing the logic be­hind con­tin­u­ing with the ring vac­ci­na­tion, John-Arne Røt­tin­gen, di­rec­tor of the di­vi­sion of In­fec­tious Dis­ease Con­trol at the Nor­we­gian In­sti­tute of Public Health and chair of the study steer­ing group, said: “The premise is that by vac­ci­nat­ing all peo­ple who have come into con­tact with an in­fected per­son, you cre­ate a pro­tec­tive ‘ring’ and stop the virus from spread­ing fur­ther.

“This strat­egy has helped us to fol­low the dis­persed epi­demic in Guinea, and will pro­vide a way to con­tinue this as a public health in­ter­ven­tion in trial mode,” said Røt­tin­gen.

At the same time as the ring vac­ci­na­tion strat­egy is be­ing con­ducted, in­ter­na­tional aid or­gan­i­sa­tion Doc­tors With­out Borders will con­duct a trial of the same vac­cine on front­line work­ers.

Ber­trand Draguez, med­i­cal di­rec­tor at Doc­tors With­out Borders, said: “These peo­ple have worked tire­lessly and put their lives at risk ev­ery day to take care of sick peo­ple. If the vac­cine is ef­fec­tive, then we are al­ready pro­tect­ing them from the virus. With such high ef­fi­cacy, all af­fected coun­tries should im­me­di­ately start and mul­ti­ply ring vac­ci­na­tions to break chains of trans­mis­sion and vac­ci­nate all front­line work­ers to pro­tect them.”

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