A phase-3 trial in children aged between nine months and 12 years carried out in Malawi, Africa.
It is a typhoid fever-endemic setting, has shown that efficacy of the Hyderabad-based Bharat Biotech’s conjugate typhoid toxoid vaccine — Typbar — lasts for at least four years.
The efficacy of the vaccine was seen in children of all age groups studied.
Children were vaccinated with a single dose of the vaccine during the period February to September 2018.
In 2019, there were an estimated 9·24 million typhoid cases and 1,10,000 deaths across the world.
The majority of the typhoid cases and deaths in 2019 occurred in South-East Asia and Africa.
6·1 typhoid infections per 1,000 vaccinated children, corresponding to a number needed to vaccinate 163 to prevent one case of typhoid fever”.
The estimated cumulative vaccine efficacy was found to be 83·4% after one year, 80·7% after two years, 80·1% after three years, 77·1% after four years, and 78·3% after 4·61 years (the longest follow-up observed) following vaccination.
Currently, there are two conjugated typhoid vaccines —the Typbar TCV typhoid vaccine manufactured byBharat Biotech that received WHO prequalification in 2017, and Biological E’s Vi-CRM197 conjugated typhoid vaccine, which received WHO prequalification in 2020.
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