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1599449 
Journal Article 
Large scale field trial of Ty21a live oral typhoid vaccine in enteric coated capsule formulation 
Levine, MM; Black, RE; Ferreccio, C; Germanier, R 
1987 
1 
The Lancet
ISSN: 0140-6736
EISSN: 1474-547X 
IPA/87/745061 
VOL 1 ISS May 9 1987 
REF 34 
1049-1052 
eng 
IPA COPYRIGHT: ASHP A placebo controlled randomized double blind trial of Ty21a attenuated Salmonella typhi oral vaccine (1-3 x 109 viable vaccine organisms/dose) was carried out in 190,000 school children in Santiago, Chile. The children were divided into 5 comparable groups. Group A received 3 doses of vaccine with sodium bicarbonate with 2 days between the doses. Group B swallowed 3 doses of lyophilized vaccine in enteric coated capsules, with 2 days between the doses. Hydroxypropyl methylcellulose phthalate was the enteric coating used to make the gelatin capsules acid resistant. Group C received 3 doses of vaccine in enteric coated capsules with 21 days between the doses. Group D ingested 3 doses of the commercial gelatin capsule/bicarbonate formulation with 21 days between the doses while Group E received 3 doses of placebo (in identical capsule as described above) with 2 days between the doses. Results showed that 3 doses, given within one wk, of Ty21a attenuated Salmonella typhi oral vaccine in an enteric coated formulation provided 67% efficacy for at least 3 yr. Increasing the interval between doses to 21 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. It was concluded that Ty21a may be regarded as a practical health tool in controlling typhoid fever. 
Typhoid vaccines; oral; enteric coated; Sodium bicarbonate; effects; typhoid vaccines; Hydroxypropyl methylcellulose phthalate; coatings; enteric; Dosage forms; oral immunization; Drug administration routes; Capsules; Dosage schedules; oral immunization; Toxicity; enteric coated capsules; Pediatrics; immunization; Chile; immunization; typhoid; oral vaccines; enteric; typhoid vaccines; Lyophilization; Equivalency; Vaccines; HUMAN