▁small ▁supply ▁of ▁the ▁pol io ▁v acc ine ▁for ▁its ▁first ▁human ▁use . ▁Meanwhile , ▁Le one ▁N . ▁Far rell , ▁also ▁a ▁research er ▁at ▁Con n aught ▁and ▁one ▁of ▁the ▁few ▁women ▁to ▁ear n ▁a ▁Ph . D . ▁in ▁the ▁sciences ▁in ▁the ▁first ▁half ▁of ▁the ▁tw enti eth ▁century , ▁led ▁progress ▁in ▁large - scale ▁production ▁methods . ▁In ▁early ▁July ▁ 1 9 5 3 , ▁National ▁Foundation ▁for ▁Inf ant ile ▁Par al ysis ▁spons ored ▁a ▁mass ▁field ▁trial ▁across ▁ 4 4 ▁U . S . ▁States , ▁Canada , ▁and ▁Hels ink i , ▁Finland . ▁Con n aught ▁became ▁responsible ▁for ▁the ▁field ▁trial ▁supply ▁of ▁bulk ▁pol i ov irus ▁flu ids , ▁and ▁sh ipped ▁out ▁some ▁ 3 , 0 0 0 ▁lit res ▁of ▁it . ▁On ▁April ▁ 1 2 , ▁ 1 9 5 5 , ▁the ▁v acc ine ▁was ▁announced ▁to ▁be ▁ 6 0 - 9 0 % ▁effective ▁against ▁the ▁three ▁ant igen ic ▁types ▁of ▁pol i ov irus ▁and ▁was ▁immediately ▁lic ensed ▁for ▁use ▁in ▁U . S . ▁and ▁Canada . ▁ ▁In ▁the ▁U . S ., ▁lic enses ▁for ▁v acc ine ▁production ▁was ▁granted ▁to ▁five ▁ph arma ce ut ical ▁companies : ▁Eli ▁L illy , ▁Par ke - D av is , ▁Wy eth , ▁Pit man - Mo ore , ▁and ▁C utter . ▁Short ly