, a publication of the Massachusetts Medical Society, Waltham, MA, USA.
, which attacks the gut
and is spread through contaminated food and water.
causes 11-21 million cases and 117,000-161,000 deaths annually worldwide.
It is a huge public health problem in Kathmandu, the Capital of
Nepal, where it is responsible for approximately 45 percent of all bloodstream infections in children
incidence of typhoid in Kathmandu is highest in the months of July and August
and lowest during the winter months. The annual incidence of typhoid in
Kathmandu varies between 297 and 449 per 100,000 population.
increased public health threat of typhoid has occurred due to emergence of
, not just in
Nepal, but also in other countries in South Asia, including India, Bangladesh
Background of the Study
The use of typhoid vaccines
typhoid fever was recommended by the World Health Organization (WHO) way back
in 2008. However, although several typhoid vaccines have been developed since
then, none of them were successful in preventing typhoid fever.
In recent years,
a new generation of typhoid conjugate vaccines has been developed in which a Salmonella typhi
antigen is conjugated
(attached) to a tetanus-toxin protein that acts as a carrier for the antigen.
One of these typhoid conjugate vaccines has been found to be highly
immunogenic, safe and efficacious in both children and adults. However, data
from clinical trials in typhoid endemic areas is still lacking. The present
clinical trial attempted to fill this lacuna in knowledge.
Key Features of the Study
- This was a Phase III, double-blind, randomized,
controlled trial, meaning that it was very well-designed, highly rigorous
and adhered to stringent protocol
- The clinical trial was conducted in Lalitpur
Metropolitan City in the Kathmandu Valley in Nepal
- The study period was from 20th November
2017 to 9th April 2018
- 20,019 healthy children between the ages of 9
months and 16 years were included in the trial
- The children were assigned to the following two
Group: This group received the tetanus-toxoid conjugated Vi
polysaccharide typhoid vaccine (Typbar-TCV) manufactured by Bharat Biotech
International, Hyderabad, India
Group: This group received the meningococcal capsular group A
conjugate vaccine (MenAfriVac) manufactured by Serum Institute of India,
- The total follow-up period after vaccination was
Key Findings of the Study
- A single dose of the typhoid vaccine was highly
immunogenic and efficacious
- A single dose of the typhoid vaccine led to a
reduction of 82 percent in the incidence of typhoid fever
- The immunogenicity of the typhoid vaccine was very
high and elicited antibodies within 1 month of vaccination
- The typhoid vaccine was safe as adverse reactions
It may be concluded
that the typhoid conjugate vaccine is a highly immunogenic, safe and effective
for vaccinating children living in endemic areas, who are at high risk
of developing typhoid fever.
The study was
funded by the Bill & Melinda Gates Foundation, Seattle, Washington, USA.
- Phase 3 Efficacy Analysis of a Typhoid Conjugate Vaccine Trial in Nepal - (https://www.nejm.org/doi/full/10.1056/NEJMoa1905047)