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Effectiveness of Vi capsular polysaccharide typhoid vaccine among children: a cluster randomized trial in Karachi, Pakistan.
Vaccine. 2012 Aug 03; 30(36):5389-95.V

Abstract

BACKGROUND

Typhoid fever is endemic in Karachi, with an incidence among children ranging from 170 to 450 per 100,000 child-years. Vaccination strategies are important for prevention, and the Vi capsular polysaccharide (ViCPS) vaccine has been shown to be effective in reducing the burden of typhoid fever.

METHODS

A cluster randomized trial was conducted in three low socioeconomic urban squatter settlements in Karachi, Pakistan between 2002 and 2007. Subsamples were followed up for assessment of immune response and adverse events after vaccination.

RESULTS

The study participants were similar in a wide variety of socio-demographic and economic characteristics at baseline. A total of 27,231 individuals of the total target population of 51,965 in 120 clusters either received a ViCPS vaccine (13,238 [52% coverage]) or the control Hepatitis A vaccine (13,993 [53%]). Typhoid fever was diagnosed in 30 ViCPS vaccine recipients and 49 Hepatitis A vaccine recipients with an adjusted total protective effectiveness of 31% (95%CI: -28%, 63%). The adjusted total vaccine protective effectiveness was -38% (95%CI: -192%, 35%) for children aged 2-5 years and 57% (95%CI: 6%, 81%) for children 5-16 years old.

CONCLUSION

The ViCPS vaccine did not confer statistically significant protection to children in the study areas, and there was a decline in antibody response 2 years post-vaccination. However, the ViCPS vaccine showed significant total protection in children 5-16 years of age, which is consistent with other studies of ViCPS vaccine conducted in India, Nepal, China and South Africa. These findings suggest that ViCPS vaccination of school-aged children will protect the children of urban, typhoid endemic areas against typhoid fever.

Authors+Show Affiliations

International Vaccine Institute, Seoul, Republic of Korea.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Clinical Trial
Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

22721899

Citation

Khan, M Imran, et al. "Effectiveness of Vi Capsular Polysaccharide Typhoid Vaccine Among Children: a Cluster Randomized Trial in Karachi, Pakistan." Vaccine, vol. 30, no. 36, 2012, pp. 5389-95.
Khan MI, Soofi SB, Ochiai RL, et al. Effectiveness of Vi capsular polysaccharide typhoid vaccine among children: a cluster randomized trial in Karachi, Pakistan. Vaccine. 2012;30(36):5389-95.
Khan, M. I., Soofi, S. B., Ochiai, R. L., Habib, M. A., Sahito, S. M., Nizami, S. Q., Acosta, C. J., Clemens, J. D., & Bhutta, Z. A. (2012). Effectiveness of Vi capsular polysaccharide typhoid vaccine among children: a cluster randomized trial in Karachi, Pakistan. Vaccine, 30(36), 5389-95. https://doi.org/10.1016/j.vaccine.2012.06.015
Khan MI, et al. Effectiveness of Vi Capsular Polysaccharide Typhoid Vaccine Among Children: a Cluster Randomized Trial in Karachi, Pakistan. Vaccine. 2012 Aug 3;30(36):5389-95. PubMed PMID: 22721899.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effectiveness of Vi capsular polysaccharide typhoid vaccine among children: a cluster randomized trial in Karachi, Pakistan. AU - Khan,M Imran, AU - Soofi,Sajid Bashir, AU - Ochiai,R Leon, AU - Habib,Mohammad Atif, AU - Sahito,Shah Muhammad, AU - Nizami,S Qamaruddin, AU - Acosta,Camilo J, AU - Clemens,John D, AU - Bhutta,Zulfiqar A, AU - ,, Y1 - 2012/06/18/ PY - 2012/04/01/received PY - 2012/06/06/revised PY - 2012/06/06/accepted PY - 2012/6/23/entrez PY - 2012/6/23/pubmed PY - 2012/12/22/medline SP - 5389 EP - 95 JF - Vaccine JO - Vaccine VL - 30 IS - 36 N2 - BACKGROUND: Typhoid fever is endemic in Karachi, with an incidence among children ranging from 170 to 450 per 100,000 child-years. Vaccination strategies are important for prevention, and the Vi capsular polysaccharide (ViCPS) vaccine has been shown to be effective in reducing the burden of typhoid fever. METHODS: A cluster randomized trial was conducted in three low socioeconomic urban squatter settlements in Karachi, Pakistan between 2002 and 2007. Subsamples were followed up for assessment of immune response and adverse events after vaccination. RESULTS: The study participants were similar in a wide variety of socio-demographic and economic characteristics at baseline. A total of 27,231 individuals of the total target population of 51,965 in 120 clusters either received a ViCPS vaccine (13,238 [52% coverage]) or the control Hepatitis A vaccine (13,993 [53%]). Typhoid fever was diagnosed in 30 ViCPS vaccine recipients and 49 Hepatitis A vaccine recipients with an adjusted total protective effectiveness of 31% (95%CI: -28%, 63%). The adjusted total vaccine protective effectiveness was -38% (95%CI: -192%, 35%) for children aged 2-5 years and 57% (95%CI: 6%, 81%) for children 5-16 years old. CONCLUSION: The ViCPS vaccine did not confer statistically significant protection to children in the study areas, and there was a decline in antibody response 2 years post-vaccination. However, the ViCPS vaccine showed significant total protection in children 5-16 years of age, which is consistent with other studies of ViCPS vaccine conducted in India, Nepal, China and South Africa. These findings suggest that ViCPS vaccination of school-aged children will protect the children of urban, typhoid endemic areas against typhoid fever. SN - 1873-2518 UR - https://www.unboundmedicine.com/medline/citation/22721899/Effectiveness_of_Vi_capsular_polysaccharide_typhoid_vaccine_among_children:_a_cluster_randomized_trial_in_Karachi_Pakistan_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0264-410X(12)00856-0 DB - PRIME DP - Unbound Medicine ER -