# Country-level perspectives and priorities to guide the development of Invasive non-Typhoidal Salmonella (iNTS) vaccines: Insights from seven countries

## TL;DR

This paper explores how seven low- and middle-income countries view the need for and development of vaccines against invasive non-typhoidal Salmonella (iNTS), emphasizing the importance of stakeholder input and combination vaccines.

## Contribution

The study provides country-level insights and priorities for iNTS vaccine development, focusing on stakeholder preferences and challenges in low-resource settings.

## Key findings

- Stakeholders emphasized the need for robust epidemiological data to accurately assess iNTS disease burden.
- Combination vaccines, such as those including iNTS and typhoid conjugate vaccine (TCV), are preferred to simplify delivery logistics.
- National stakeholder engagement is critical to ensure vaccines align with country-specific needs and challenges.

## Abstract

Invasive non-typhoidal Salmonella (iNTS) disease typically presents as a non-specific febrile illness that can progress to bloodstream infections and carries a high case fatality rate. Early detection improves patient outcomes, however, in resource-constrained settings, limited diagnostic capacity leads to underdiagnosis, insufficient incidence data, and incomplete epidemiological and socio-economic research on iNTS. Although no licensed vaccines currently exist, several candidates are in pre-clinical and clinical development. In the early stages of vaccine development, it is essential to consider country-level perspectives and priorities to guide the development of novel vaccines. To support this, the World Health Organization’s Vaccine Innovation Framework was applied to conduct a consultation with 40 stakeholders representing the national immunization programmes in Burkina Faso, Ghana the Gambia, the Democratic Republic of the Congo (DRC), Kenya, Malawi and Mozambique. The consultation aimed to assess the stakeholder perceptions on the need for an iNTS vaccine and to evaluate its desirability, suitability, and evidence requirements from a low- and middle-income country (LMIC) perspective. Stakeholders argued that although an iNTS vaccines is desirable, the lack of nationally available epidemiological data is a barrier to accurately understanding the disease burden. A novel vaccine would be more desirable if it aligns with the preferred product characteristics specified, and helps mitigate, rather than exacerbate, current immunization programme challenges. They also expressed a preference for combination vaccines that align programmatically, including formulations combining iNTS with typhoid conjugate vaccine (TCV), to reduce the number of injections and simplify delivery logistics. To make evidence-based decisions on potential introduction, stakeholders emphasized the need for robust data on the value and impact of iNTS vaccines.

Invasive non-typhoidal Salmonella (iNTS) disease causes severe bloodstream infections, resulting in high mortality, especially among children, and in low income countries. Limited diagnostic capacity contributes to underdiagnosis and insufficient data on disease burden. Currently, there are several vaccine candidates in development. To inform early vaccine development, we applied the World Health Organization’s Vaccine Innovation Framework to consult 40 national stakeholders from Burkina Faso, the Gambia, the Democratic Republic of the Congo, Kenya, Malawi and Mozambique. Stakeholders argued that although iNTS vaccine is desirable, the lack of national epidemiological data is a key barrier to assessing true need. Stakeholders emphasized that given the increasing number of vaccines in the immunization schedule, they would prefer novel combination vaccines, including iNTS and typhoid conjugate vaccine (TCV). Engaging national stakeholders early in vaccine development helps ensure that future iNTS vaccines are aligned with the needs and priorities of the countries where the disease is most prevalent.