Single-Dose Typhoid Conjugate Vaccine Safe and Effective for Kids 6 Months and Older

Group of children smiling at the camera

This post was originally published on the Take On Typhoid website. Take On Typhoid is an initiative of the Typhoid Vaccine Acceleration Consortium (TyVAC), a partnership between the Center for Vaccine Development and Global Health at the University of Maryland School of Medicine, the Oxford Vaccine Group at the University of Oxford, and PATH, and Sabin’s Coalition against Typhoid.  

Typhoid continues to disproportionately impact children living in endemic areas, such as Malawi. TCV is a safe and cost-effective tool to address the substantial burden of disease and protect children living in high-risk countries.

TCV offers protection for more than 4 years

TyVAC conducted a series of clinical trials to understand TCV performance in diverse populations. Previous data from a large randomized controlled trial led by Malawi-Liverpool-Wellcome Trust (MLW) showed a single dose of TCV is safe and more than 80% effective in protecting against typhoid for 18-24 months in Malawi. The study continued and new data show TCV prevents blood culture-confirmed typhoid for more than 4 years among children aged 9 months-12 years.

Between February and September 2018, healthy children were randomly assigned in a 1:1 ratio to receive a single dose of TCV or meningococcal capsular group A conjugate (MenA) vaccine. The MLW team conducted passive surveillance at four sites where vaccinated participants would be tested for typhoid and other pathogens if they presented with a fever.

A total of 24 children in the TCV group and 110 children in the MenA group had a positive blood culture for Salmonella Typhi, the causative agent of typhoid. The overall vaccine efficacy of TCV – after more than 4 years – was 78%, with an estimated 1.3% decline in efficacy per year. Efficacies by age-group were approximately 71% in children aged 9 months to < 2 years, and 79-80% in children 2 to < 5 years, and 5 to 12 years.

Impact of the data

With increasing drug resistance, climate change, extreme weather events, and urbanization, the need to control typhoid is urgent. As the corresponding commentary highlights, the findings from this study reinforce what we already know – a single dose of TCV is safe, well-tolerated, and effective at protecting against typhoid. And, these critical longer-term data further support the cost-effectiveness of TCV. These results offer promise of saving lives and continued hope that decision-makers will prioritize TCV introduction to Take on Typhoid.

Read the full commentary written by International Vaccine Institute.