Research priorities to support typhoid conjugate vaccine decision-making in India: evidence assessment and...

India has a high typhoid fever burden. In 2022, the National Technical Advisory Group on Immunisation recommended introducing typhoid conjugate vaccine (TCV) into the Universal Immunisation Programme. Our study aims to identify research priorities to support ongoing TCV decision-making in India.

We identified 45 evidence factors for TCV decision-making in India by adapting WHO's Evidence-to-Recommendation framework. We assigned an evidence gap score for each evidence factor from 0 (low) to 4 (high) based on the availability and sufficiency, quality, breadth and applicability of evidence identified in a literature review (end date 30 November 2023). We assigned each evidence factor an importance score based on the results of an online survey conducted among national immunisation stakeholders (n=22, 1 July 2023-31 October 2023), where they ranked the importance of seven WHO's Evidence-to-Recommendation criteria and several evidence factors within them. We rescaled mean stakeholder rankings into importance scores from 0 (low) to 4 (high). Finally, we added the evidence gap score to the importance score and used the overall scores to identify research priorities to support ongoing TCV decision-making in India.

We estimated the highest evidence priority scores for public perception of typhoid fever, vaccination budget impact, vaccine availability, socioeconomic impact, fiscal space, antimicrobial resistance tracking, typhoid fever mortality, public perception of TCV, immunisation managers' acceptance and vaccine schedule preferences among caregivers.

By adapting WHO's Evidence-to-Recommendation framework to the Indian context, we systematically identified several research priorities to support ongoing decision-making on TCV in India. These priorities will evolve as new research studies and questions emerge about the optimal scheduling, roll-out and implementation of TCV in India.