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Lancet. 1987 May 9;1(8541):1049-52.

Large-scale field trial of Ty21a live oral typhoid vaccine in enteric-coated capsule formulation.


Three doses, given within one week, of Ty21a attenuated Salmonella typhi oral vaccine in an enteric-coated formulation provided 67% efficacy for at least 3 years in a randomised, placebo-controlled field trial involving 109,000 schoolchildren in Santiago, Chile. Increasing the interval between doses to twenty-one days did not enhance protection. Significantly less protection followed administration of vaccine in gelatin capsules with sodium bicarbonate. Ty21a provides the same level of protection as the heat/phenol-inactivated whole cell parenteral vaccine but differs in not causing adverse reactions. Ty21a may now be regarded as a practical public health tool.

[Indexed for MEDLINE]

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