▁developing ▁countries , ▁and ▁approximately ▁ 1 0 % ▁suffer ▁severe ▁health ▁comp lications ▁from ▁the ▁in fection . ▁While ▁chem oth ere pe ut ic ▁dru gs , ▁such ▁as ▁pra zi quant el , ▁ox am ni qu ine ▁and ▁met rif on ate ▁both ▁no ▁longer ▁on ▁the ▁market , ▁are ▁currently ▁considered ▁safe ▁and ▁effective ▁for ▁the ▁treatment ▁of ▁sch ist os om ias is , ▁rein fection ▁occurs ▁frequently ▁following ▁drug ▁treatment , ▁thus ▁a ▁v acc ine ▁is ▁sought ▁to ▁provide ▁long - term ▁treatment . ▁ ▁Additionally , ▁experimental ▁v acc ination ▁efforts ▁have ▁been ▁successful ▁in ▁animal ▁models ▁of ▁sch ist os om ias is . ▁ ▁Param y os in ▁has ▁been ▁proposed ▁as ▁a ▁v acc ine ▁candidate . ▁ ▁At ▁present ▁Sm - p 8 0 ▁( cal p ain ) ▁is ▁the ▁sole ▁sch ist os ome ▁v acc ine ▁candidate ▁that ▁has ▁been ▁tested ▁for ▁its ▁pro phy la ctic ▁and ▁ant if ec und ity ▁effic acy ▁in ▁different ▁v acc ine ▁form ulations ▁and ▁approaches ▁( e . g ., ▁DNA ▁alone , ▁recom bin ant ▁protein ▁and ▁prime ▁boost ) ▁in ▁two ▁very ▁different ▁experimental ▁animal ▁models ▁( mouse ▁and ▁b ab oon ) ▁of ▁in fection ▁and ▁disease . ▁Sm - p 8 0 - based ▁v acc ine ▁form ulation ( s ) ▁have ▁four ▁effects : ▁Red u ction ▁in ▁adult ▁w orm ▁numbers ; ▁Red u ction ▁in ▁egg ▁production ▁( complete ▁elim