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Comparison of Strategies and Incidence Thresholds for Vi Conjugate Vaccines Against Typhoid Fever: A Cost-effectiveness Modeling Study.
J Infect Dis. 2018 11 10; 218(suppl_4):S232-S242.JI

Abstract

Background

Typhoid fever remains a major public health problem globally. While new Vi conjugate vaccines hold promise for averting disease, the optimal programmatic delivery remains unclear. We aimed to identify the strategies and associated epidemiologic conditions under which Vi conjugate vaccines would be cost-effective.

Methods

We developed a dynamic, age-structured transmission and cost-effectiveness model that simulated multiple vaccination strategies with a typhoid Vi conjugate vaccine from a societal perspective. We simulated 10-year vaccination programs with (1) routine immunization of infants (aged <1 year) through the Expanded Program on Immunization (EPI) and (2) routine immunization of infants through the EPI plus a 1-time catch-up campaign in school-aged children (aged 5-14 years). In the base case analysis, we assumed a 0.5% case-fatality rate for all cases of clinically symptomatic typhoid fever and defined strategies as highly cost-effective by using the definition of a low-income country (defined as a country with a gross domestic product of $1045 per capita). We defined incidence as the true number of clinically symptomatic people in the population per year.

Results

Vi conjugate typhoid vaccines were highly cost-effective when administered by routine immunization activities through the EPI in settings with an annual incidence of >50 cases/100000 (95% uncertainty interval, 40-75 cases) and when administered through the EPI plus a catch-up campaign in settings with an annual incidence of >130 cases/100000 (95% uncertainty interval, 50-395 cases). The incidence threshold was sensitive to the typhoid-related case-fatality rate, carrier contribution to transmission, vaccine characteristics, and country-specific economic threshold for cost-effectiveness.

Conclusions

Typhoid Vi conjugate vaccines would be highly cost-effective in low-income countries in settings of moderate typhoid incidence (50 cases/100000 annually). These results were sensitive to case-fatality rates, underscoring the need to consider factors contributing to typhoid mortality (eg, healthcare access and antimicrobial resistance) in the global vaccination strategy.

Authors+Show Affiliations

Division of Infectious Diseases and Geographic Medicine, California. Division of Epidemiology, Stanford University School of Medicine, California.Division of Infectious Diseases and Geographic Medicine, California.Institute for Health Metrics and Evaluation, University of Washington, Seattle.Typhoid Programs, Sabin Vaccine Institute, Washington, D. C.Department of Medicine, University of Toronto, Washington, D. C. Division of Internal Medicine, Toronto General Hospital, University Health Network, Toronto, Canada. Division of Infectious Diseases, Toronto General Hospital, University Health Network, Toronto, Canada.Division of Infectious Diseases and Geographic Medicine, California.Division of Infectious Diseases and Geographic Medicine, California.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

29444257

Citation

Lo, Nathan C., et al. "Comparison of Strategies and Incidence Thresholds for Vi Conjugate Vaccines Against Typhoid Fever: a Cost-effectiveness Modeling Study." The Journal of Infectious Diseases, vol. 218, no. suppl_4, 2018, pp. S232-S242.
Lo NC, Gupta R, Stanaway JD, et al. Comparison of Strategies and Incidence Thresholds for Vi Conjugate Vaccines Against Typhoid Fever: A Cost-effectiveness Modeling Study. J Infect Dis. 2018;218(suppl_4):S232-S242.
Lo, N. C., Gupta, R., Stanaway, J. D., Garrett, D. O., Bogoch, I. I., Luby, S. P., & Andrews, J. R. (2018). Comparison of Strategies and Incidence Thresholds for Vi Conjugate Vaccines Against Typhoid Fever: A Cost-effectiveness Modeling Study. The Journal of Infectious Diseases, 218(suppl_4), S232-S242. https://doi.org/10.1093/infdis/jix598
Lo NC, et al. Comparison of Strategies and Incidence Thresholds for Vi Conjugate Vaccines Against Typhoid Fever: a Cost-effectiveness Modeling Study. J Infect Dis. 2018 11 10;218(suppl_4):S232-S242. PubMed PMID: 29444257.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Comparison of Strategies and Incidence Thresholds for Vi Conjugate Vaccines Against Typhoid Fever: A Cost-effectiveness Modeling Study. AU - Lo,Nathan C, AU - Gupta,Ribhav, AU - Stanaway,Jeffrey D, AU - Garrett,Denise O, AU - Bogoch,Isaac I, AU - Luby,Stephen P, AU - Andrews,Jason R, PY - 2018/2/15/pubmed PY - 2019/9/20/medline PY - 2018/2/15/entrez SP - S232 EP - S242 JF - The Journal of infectious diseases JO - J Infect Dis VL - 218 IS - suppl_4 N2 - Background: Typhoid fever remains a major public health problem globally. While new Vi conjugate vaccines hold promise for averting disease, the optimal programmatic delivery remains unclear. We aimed to identify the strategies and associated epidemiologic conditions under which Vi conjugate vaccines would be cost-effective. Methods: We developed a dynamic, age-structured transmission and cost-effectiveness model that simulated multiple vaccination strategies with a typhoid Vi conjugate vaccine from a societal perspective. We simulated 10-year vaccination programs with (1) routine immunization of infants (aged <1 year) through the Expanded Program on Immunization (EPI) and (2) routine immunization of infants through the EPI plus a 1-time catch-up campaign in school-aged children (aged 5-14 years). In the base case analysis, we assumed a 0.5% case-fatality rate for all cases of clinically symptomatic typhoid fever and defined strategies as highly cost-effective by using the definition of a low-income country (defined as a country with a gross domestic product of $1045 per capita). We defined incidence as the true number of clinically symptomatic people in the population per year. Results: Vi conjugate typhoid vaccines were highly cost-effective when administered by routine immunization activities through the EPI in settings with an annual incidence of >50 cases/100000 (95% uncertainty interval, 40-75 cases) and when administered through the EPI plus a catch-up campaign in settings with an annual incidence of >130 cases/100000 (95% uncertainty interval, 50-395 cases). The incidence threshold was sensitive to the typhoid-related case-fatality rate, carrier contribution to transmission, vaccine characteristics, and country-specific economic threshold for cost-effectiveness. Conclusions: Typhoid Vi conjugate vaccines would be highly cost-effective in low-income countries in settings of moderate typhoid incidence (50 cases/100000 annually). These results were sensitive to case-fatality rates, underscoring the need to consider factors contributing to typhoid mortality (eg, healthcare access and antimicrobial resistance) in the global vaccination strategy. SN - 1537-6613 UR - https://www.unboundmedicine.com/medline/citation/29444257/Comparison_of_Strategies_and_Incidence_Thresholds_for_Vi_Conjugate_Vaccines_Against_Typhoid_Fever:_A_Cost_effectiveness_Modeling_Study_ L2 - https://academic.oup.com/jid/article-lookup/doi/10.1093/infdis/jix598 DB - PRIME DP - Unbound Medicine ER -