Impact and cost-effectiveness of new tuberculosis vaccines in low- and middle-income countries

Abstract

To help reach the target of tuberculosis (TB) disease elimination by 2050, vaccine development needs to occur now. We estimated the impact and cost-effectiveness of potential TB vaccines in low- and middle-income countries using an age-structured transmission model. New vaccines were assumed to be available in 2024, to prevent active TB in all individuals, to have a 5-y to lifetime duration of protection, to have 40-80% efficacy, and to be targeted at "infants" or "adolescents/adults." Vaccine prices were tiered by income group (US $1.50-$10 per dose), and cost-effectiveness was assessed using incremental cost per disability adjusted life year (DALY) averted compared against gross national income per capita. Our results suggest that over 2024-2050, a vaccine targeted to adolescents/adults could have a greater impact than one targeted at infants. In low-income countries, a vaccine with a 10-y duration and 60% efficacy targeted at adolescents/adults could prevent 17 (95% range: 11-24) million TB cases by 2050 and could be considered cost-effective at $149 (cost saving to $387) per DALY averted. If targeted at infants, 0.89 (0.42-1.58) million TB cases could be prevented at $1,692 ($634-$4,603) per DALY averted. This profile targeted at adolescents/adults could be cost-effective at $4, $9, and $20 per dose in low-, lower-middle-, and upper-middle-income countries, respectively. Increased investments in adult-targeted TB vaccines may be warranted, even if only short duration and low efficacy vaccines are likely to be feasible, and trials among adults should be powered to detect low efficacies.

Keywords: epidemiology; mathematical modeling; threshold analysis.

Fig. 1.

Model calibration (A–C) and vaccine impact (D and E) in LICs. In A–C, the median (solid black line) and 95% range (gray cloud) of model fits to data (red, cross and range) are shown. (A) Human population size (in 1,000s) in LICs for the years 2000–2050. (B) TB incidence (cases per 100,000 per year) for the years 2000–2050. (C) TB mortality (deaths per 100,000 per year) for the years 2000–2050. TB incidence (cases per 100,000 per year) for the years 2000–2050 with the median model output (black line) and vaccine profile impact. Characteristics of efficacy (color) and duration of protection (line type) are shown for vaccines targeted at infants (D) or adolescent/adults (E). A vaccine targeted at infants (D) has a smaller impact on TB disease incidence than one targeted at adolescents/adults (E). In E, “waves” within the adolescent/adult incidence are due to mass campaigns.

Fig. 2.

Vaccine targeted at adolescents/adults can cost more per dose than one targeted at infants and still be cost-effective. The contour plots shown here are of the cost-effective vaccine price (US dollars) that results in the cost per DALY for a vaccine, of a certain duration and efficacy, equal to the mean GNI per capita. The color represents the price as indicated in the legend. The dashed black line represents the values below which no price would be cost-effective. For example, if given in LICs, an adolescent/adult vaccine with a 15-y duration of protection and 60% efficacy could be cost-effective when priced at ∼$7.