ine ▁ 1 0 0 ▁percent ▁effect iveness ▁after ▁tests ▁on ▁ 4 0 0 0 ▁people ▁in ▁Guinea ▁who ▁had ▁been ▁in ▁close ▁contact ▁with ▁E bol a ▁patients . ▁However , ▁a ▁study ▁spons ored ▁by ▁the ▁National ▁Instit utes ▁of ▁Health , ▁the ▁Food ▁and ▁D rug ▁Administration ▁and ▁the ▁U . S . ▁Department ▁of ▁Health ▁and ▁Human ▁Services , ▁and ▁conducted ▁by ▁research ers ▁from ▁the ▁U . S . ▁National ▁Academy ▁of ▁Medicine , ▁called ▁the ▁v acc ine ’ s ▁effect iveness ▁in ▁prevent ing ▁E bol a ▁in fe ctions ▁into ▁question . ▁In ▁particular , ▁the ▁authors ▁critic ized ▁the ▁method ology ▁of ▁the ▁patient ▁trail , ▁and ▁argued ▁that ▁the ▁protection ▁provided ▁by ▁the ▁v acc ine ▁may ▁be ▁lower ▁than ▁officially ▁announced . ▁ ▁The ▁W HO ▁approved ▁the ▁v acc ine ▁for ▁use ▁in ▁the ▁on going ▁E bol a ▁out break ▁on ▁May ▁ 2 9 , ▁ 2 0 1 7 . ▁ ▁It ▁was ▁announced ▁in ▁May ▁ 2 0 1 7 ▁that ▁the ▁Gam ale ya ▁Center ▁for ▁Ep ide mi ology ▁and ▁Micro bi ology ▁in ▁Russia ▁would ▁deliver ▁ 1 0 0 0 ▁dos es ▁of ▁an ▁independently ▁produced ▁v acc ine ▁to ▁Guinea ▁for ▁testing . ▁According ▁to ▁a ▁X in h ua ▁report , ▁it ▁is ▁the ▁only ▁officially ▁author ized ▁and ▁approved ▁E bol a ▁v acc ine ▁for ▁clin ical ▁use ▁to ▁date . ▁ ▁Works ▁derived ▁from ▁the ▁E bol