Effectiveness of the TYPHIBEV® (Vi-CRM197 conjugate) Vaccine Introduction in Nepal: A Test-Negative, Case-Control Study

Q: What does this research mean for the field?

The TYPHIBEV vaccine demonstrated 89% effectiveness in preventing blood culture-confirmed typhoid fever among vaccinated children in Nepal. Novelty: ClaimNovelty.CONFIRMATORY. Consensus alignment: ConsensusAlignment.SUPPORTS_CONSENSUS.

Dipesh Tamrakar; Sabin Bikram Shahi; Esther Jung; Shivram Naga; Basudha Shrestha; Pratibha Bista Roka; Rabin Sharma Pokharel; Ram Hari Chapagain; Akhil Tamrakhar; Manoj Mahato; Surendra Kumar Madhup; Georgi Shukarev; Kate Doyle; Isaac I. Bogoch; Stephen P. Luby; Denise O. Garrett; Wirongrong Cheirakul; Jason R. Andrews

doi:10.1016/j.jinf.2026.106719

March 1, 2026Journal of InfectionOpen Access

Effectiveness of the TYPHIBEV® (Vi-CRM197 conjugate) Vaccine Introduction in Nepal: A Test-Negative, Case-Control Study

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Key result

TYPHIBEV vaccine shows ~89% effectiveness against confirmed typhoid fever in children.

Why the study?

To evaluate the effectiveness of TYPHIBEV introduced through a catch-up campaign and routine immunization in Nepal in preventing blood culture-confirmed typhoid fever among children.

Does the TYPHIBEV vaccine prevent blood culture-confirmed typhoid fever in children aged 15 months to 15 years?

Key Points

The study aims to evaluate the effectiveness of the TYPHIBEV vaccine in preventing typhoid fever among children in Nepal.
Conducted a test-negative, case-control study.
Defined cases as vaccinated children testing positive for Salmonella Typhi.
Matched test-negative controls by age, location, and date of blood culture.
Calculated odds ratios using conditional logistic regression.
40 typhoid cases and 113 matched controls were enrolled.
51% of cases and 84% of controls had received the TYPHIBEV vaccine.
Vaccine effectiveness was 89% overall; 72% for children under 5 and 98% for those aged 5-15.

Structured PICO

Does the TYPHIBEV vaccine prevent blood culture-confirmed typhoid fever in children aged 15 months to 15 years?

P

Population

153 children (40 cases, 113 controls) aged 15 months to 15 years eligible for the typhoid vaccine catch-up campaign or routine immunization in Nepal, presenting with fever or sepsis and having a blood culture performed.

I

Intervention

TYPHIBEV (Vi-CRM197 conjugate) vaccine (typhoid conjugate vaccine, TCV)

C

Comparator

Unvaccinated (test-negative controls)

O

Outcome

Blood culture-confirmed typhoid fever (Salmonella Typhi)hard clinical

The TYPHIBEV typhoid conjugate vaccine is highly effective (89%) in preventing blood culture-confirmed typhoid fever among children in a real-world setting in Nepal.

Limitations

Moderate sensitivity of blood culture (approximately 60%) potentially leading to misclassification
Lack of data on antibiotic use prior to hospital presentation
Self-reported vaccination status in about one-fourth of participants introducing possible recall bias
Introduction of TCV occurred after the COVID-19 pandemic during a period of reduced typhoid transmission

Implication

Supports TYPHIBEV use in endemic pediatric immunization programs; extends prior trial efficacy to real-world effectiveness.

Discussion

No takes yet. Share an insight, caveat, or question.

Cite This Study

Tamrakar et al. (2026) studied this question. TYPHIBEV vaccine demonstrated 89% effectiveness in preventing blood culture-confirmed typhoid fever among vaccinated children in Nepal.

synapsesocial.com/papers/69b256fe96eeacc4fcec5b9d https://doi.org/10.1016/j.jinf.2026.106719

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Effectiveness of the TYPHIBEV® (Vi-CRM197 conjugate) Vaccine Introduction in Nepal: A Test-Negative, Case-Control Study

Key Points

Structured PICO

Limitations

Implication

Discussion

Cite This Study

Effectiveness of the TYPHIBEV® (Vi-CRM197 conjugate) Vaccine Introduction in Nepal: A Test-Negative, Case-Control Study

Key Points

Structured PICO

Limitations

Implication

Discussion

Cite This Study

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