#VisualAbstract: Phase 3 Efficacy Analysis of a Typhoid Conjugate Vaccine Trial in Nepal

1. In Nepal, the typhoid conjugate vaccine has proven to be very effective in protecting against typhoid fever.

2. The typhoid antibody titers more than quadrupled in the participants that received the typhoid conjugate vaccine.

Evidence Rating Level: 1 (Excellent)

Study Rundown: Typhoid fever is a bacterial infection caused by Salmonella that leads to a high fever, weakness, stomach pain, and rash. It is a major public health problem in the summer months among children in South Asian countries, such as India, Bangladesh, Pakistan, and Nepal. The oral vaccine has proven to be less effective in children than adults for multiple reasons. This randomized controlled trial was phase 3 of the typhoid conjugate vaccine to determine efficacy in Nepal, a typhoid fever endemic area. Children in this study received either the typhoid vaccine or control vaccine and were followed for 6 months. In participants who received the typhoid vaccine, typhoid fever occurred less commonly, and antibody titers were higher than the control group. Within a week of vaccination, the most common side effects were pain at the injection site, fever, vomiting, and diarrhea. The typhoid vaccine group reported less adverse events within 1 month and 6 months of the vaccine, when compared to the control group. No deaths related to the vaccine were reported.

Follow-up of these participants is on-going and is important to determine long-term efficacy and safety of the vaccine. If this vaccine proves to be effective long-term, it will be able to help prevent typhoid fever among children and travelers to high-risk countries.