Evaluating the Impact and Cost-Effectiveness of Typhoid Conjugate Vaccine Schedules Across Diverse Settings: A Multi-Model Comparison

This preprint evaluates the impact and cost-effectiveness of different typhoid conjugate vaccine (TCV) schedules across diverse epidemiological settings using a multi-model comparison. The study applies two agent-based and two compartmental transmission models, combined with economic evaluation using a net monetary benefit framework, to assess optimal vaccination strategies under varying incidence and vaccine waning scenarios. 

Key findings

• Routine vaccination at 9 months with catch-up campaigns and a booster dose at 5 years achieved the greatest health impact, reducing cases by approximately 48–64% in high-incidence settings over 10 years.
• All vaccination strategies reduced cases, hospitalizations, and deaths compared to no vaccination across all incidence scenarios.
• TCV introduction with catch-up campaigns was cost-effective in high-incidence settings at relatively low willingness-to-pay thresholds (e.g., >$100 per DALY averted in Africa scenarios).
• In very high-incidence settings, vaccination strategies were often cost-saving, with booster doses becoming cost-effective across most scenarios.
• The optimal vaccination strategy depends on local epidemiology, including incidence levels, age distribution of cases, and the rate of vaccine waning.
• Faster waning of vaccine protection shifts the optimal strategy toward later vaccination ages or inclusion of booster doses.

Thumbnail image credit: Gavi