title: Efficacy of a locally produced, Chinese Vi polysaccharide typhoid fever vaccine during six years of follow-up.
abstract: A locally produced Vi polysaccharide vaccine against typhoid fever was licensed in China following two placebo-controlled, efficacy trials conducted in the early 1990s in Baoying, Jiangsu Province, and Quan-zhou, Guangxi Province. The two trials each enrolled over 80,000 participants and followed participants for 12 and 19 months post-vaccination, respectively. To define the long-term efficacy of this vaccine, we retrospectively assessed the occurrence of typhoid fever, diagnosed with clinical and serological criteria, in the two study populations for 6 years following vaccination. During the second year following vaccination, vaccine efficacy was 100% (95% CI: 17%, 100%) in Baoying and 85% (95% CI: 49%, 96%) in Quan-zhou. There was suggestive protection (51%; PE: -95%, 88%) during the third year in Baoying, nearly identical to the level observed in the third year of an earlier trial in South Africa. These results confirm that this vaccine protects for at least 2 years, and are consistent with the assertion that the vaccine protects for at least 3 years.
authors.affiliation: International Vaccine Institute, SNU Research Park, San 4-8 Bong-Cheon 7 Dong Kwanak-Ku, Seoul 151-818, South Korea.
authors.forename: Camilo J
authors.initials: CJ
authors.lastname: Acosta
authors.forename: Yang
authors.initials: Y
authors.lastname: Hong-Hui
authors.forename: Wang
authors.initials: W
authors.lastname: Ning
authors.forename: Gao
authors.initials: G
authors.lastname: Qion
authors.forename: Deng
authors.initials: D
authors.lastname: Qun
authors.forename: Ma
authors.initials: M
authors.lastname: Xiaolei
authors.forename: Zhou
authors.initials: Z
authors.lastname: Baode
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: M Carolina
authors.initials: MC
authors.lastname: Danovaro-Holliday
authors.forename: R Leon
authors.initials: RL
authors.lastname: Ochiai
authors.forename: Xuan-Yi
authors.initials: XY
authors.lastname: Wang
authors.forename: Deok-Ryun
authors.initials: DR
authors.lastname: Kim
authors.forename: Xu
authors.initials: X
authors.lastname: Zhi-Yi
authors.forename: Dong
authors.initials: D
authors.lastname: Bai-Qing
authors.forename: Claudia M
authors.initials: CM
authors.lastname: Galindo
authors.forename: John D
authors.initials: JD
authors.lastname: Clemens
mesh_terms: D000942:Antigens, Bacterial / Q000276:immunology*; D002681:China; D005500:Follow-Up Studies; D006801:Humans; D011135:Polysaccharides, Bacterial / Q000276:immunology* / Q000627:therapeutic use*; D012189:Retrospective Studies; D016896:Treatment Outcome; D014435:Typhoid Fever / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control*; D014436:Typhoid-Paratyphoid Vaccines / Q000008:administration & dosage* / Q000276:immunology / Q000627:therapeutic use
chemical_list: D000942:Antigens, Bacterial; D011135:Polysaccharides, Bacterial; D014436:Typhoid-Paratyphoid Vaccines; C057664:Vi polysaccharide vaccine, typhoid