29 Jan 2024 • In a significant phase 3 trial, a single-dose typhoid conjugate vaccine (Vi-TT) showed sustained protection for over 4 years in children aged 9 months to 12 years.

The study noted a vaccine efficacy of 78.3%, effective across all age groups & decreasing by only 1.3% per year. This is the first randomized trial to assess the long-term efficacy of a single-dose TCV in a typhoid fever-endemic area starting from 9 months of age.

It supported current WHO recommendations in typhoid-endemic areas for mass campaigns among children aged 9mo - 15y followed by routine introduction in first 2y of life.

The longer durability of protection translates into a lower number needed to vaccinate to prevent each case of blood culture-confirmed typhoid fever.

In summary, this study has found high and durable efficacy of a single dose of Vi-TT across all age groups, providing crucial evidence for the probable cost-effectiveness and success of routine immunisation and mass vaccination campaigns in areas of high disease burden.

Source: The Lancet | Read full story