▁there after , ▁in ▁what ▁became ▁known ▁as ▁the ▁C utter ▁incident , ▁some ▁batch es ▁of ▁the ▁v acc ine ▁from ▁California ' s ▁C utter ▁Labor ator ies ▁led ▁to ▁an ▁out break ▁of ▁pol io ▁and ▁was ▁immediately ▁re called . ▁The ▁Ep ide mic ▁Int elligence ▁Service ▁of ▁the ▁Communic able ▁D ise ase ▁Center ▁found ▁that ▁two ▁production ▁po ols ▁made ▁by ▁C utter ▁L abs ▁contained ▁live ▁pol i ov irus . ▁On ▁May ▁ 7 , ▁the ▁U . S . ▁Sur geon ▁General ▁susp ended ▁the ▁country ' s ▁entire ▁v acc ine ▁program . ▁ ▁In ▁Canada , ▁Con n aught ' s ▁v acc ine ▁was ▁the ▁only ▁version ▁in ▁use , ▁and ▁had ▁demonstrated ▁no ▁cases ▁of ▁pol io ▁linked ▁with ▁its ▁production . ▁Therefore , ▁Canadian ▁use ▁of ▁the ▁v acc ine ▁continued ▁un inter rupted . ▁Political ▁and ▁public ▁health ▁confidence ▁in ▁the ▁v acc ine ▁north ▁of ▁the ▁border ▁during ▁the ▁C utter ▁incident ▁helped ▁p ave ▁the ▁way ▁for ▁the ▁U . S . ▁to ▁res ume ▁pol io ▁imm un izations ▁in ▁July ▁ 1 9 5 5 . ▁ ▁The ▁Con n aught ▁Labor ator ies ▁continued ▁to ▁improve ▁and ▁expand ▁pol io ▁v acc ine ▁production ▁during ▁the ▁latter ▁half ▁of ▁the ▁ 1 9 5 0 s ▁and ▁into ▁the ▁early ▁ 1 9 6 0 s . ▁ ▁Er adic ating ▁small po x : ▁ 1 9 6 0 s - ear