Cost-effectiveness of routine and campaign use of typhoid Vi-conjugate vaccine in Gavi-eligible countries: a modelling study. Issue 7 (July 2019)

• Record Type: Journal Article
• Authors: Bilcke, Joke; Antillón, Marina; Pieters, Zoë; Kuylen, Elise; Abboud, Linda; Neuzil, Kathleen M; Pollard, Andrew J; Paltiel, A David; Pitzer, Virginia E
• Is Part Of: Lancet infectious diseases. Volume 19:Issue 7(2019)
• Page Start: 728
• Page End: 739
• Publication Date: 2019-07
• Subjects: Communicable diseases -- Periodicals; Infection -- Periodicals; Communicable Diseases -- Periodicals; Infection -- Periodicals; Maladies infectieuses -- Périodiques; Infection -- Périodiques; Communicable diseases; Infection; Periodicals; 616.905
• DOI: 10.1016/S1473-3099(18)30804-1
• Languages: English
• ISSNs: 1473-3099

Abstract

Summary: Background: Typhoid fever is a major cause of morbidity and mortality in low-income and middle-income countries. In 2017, WHO recommended the programmatic use of typhoid Vi-conjugate vaccine (TCV) in endemic settings, and Gavi, The Vaccine Alliance, has pledged support for vaccine introduction in these countries. Country-level health economic evaluations are now needed to inform decision-making. Methods: In this modelling study, we compared four strategies: no vaccination, routine immunisation at 9 months, and routine immunisation at 9 months with catch-up campaigns to either age 5 years or 15 years. For each of the 54 countries eligible for Gavi support, output from an age-structured transmission-dynamic model was combined with country-specific treatment and vaccine-related costs, treatment outcomes, and disability weights to estimate the reduction in typhoid burden, identify the strategy that maximised average net benefit (ie, the optimal strategy) across a range of country-specific willingness-to-pay (WTP) values, estimate and investigate the uncertainties surrounding our findings, and identify the epidemiological conditions under which vaccination is optimal. Findings: The optimal strategy was either no vaccination or TCV immunisation including a catch-up campaign. Routine vaccination with a catch-up campaign to 15 years of age was optimal in 38 countries, assuming a WTP value of at least US$200 per disability-adjusted life-year (DALY) averted, or assuming a WTP value of at least 25% of each country's gross domestic product (GDP) per capita per DALY averted, at a vaccine price of $1·50 per dose (but excluding Gavi's contribution according to each country's transition phase). This vaccination strategy was also optimal in 48 countries assuming a WTP of at least $500 per DALY averted, in 51 with assumed WTP values of at least $1000, in 47 countries assuming a WTP value of at least 50% of GDP per capita per DALY averted, and in 49 assuming a minimum of 100%. Vaccination was likely to be cost-effective in countries with 300 or more typhoid cases per 100 000 person-years. Uncertainty about the probability of hospital admission (and typhoid incidence and mortality) had the greatest influence on the optimal strategy. Interpretation: Countries should establish their own WTP threshold and consider routine TCV introduction, including a catch-up campaign when vaccination is optimal on the basis of this threshold. Obtaining improved estimates of the probability of hospital admission would be valuable whenever the optimal strategy is uncertain. Funding: Bill & Melinda Gates Foundation, Research Foundation–Flanders, and the Belgian–American Education Foundation.