Towards a marketplace for Vi polysaccharide-conjugate typhoid vaccines

In The Lancet Infectious Diseases, Ganesh Kumar Rai and colleagues 1 Rai GK Saluja T Chaudhary S et al. Safety and immunogenicity of the Vi-DT typhoid conjugate vaccine in healthy volunteers in Nepal: an observer-blind, active-controlled, randomised, non-inferiority, phase 3 trial. Lancet Infect Dis. 2021; (published online Dec 20.)https://doi.org/10.1016/S1473-3099(21)00455-2 PubMed Google Scholar describe the safety and immunogenicity of a new Vi polysaccharide-diphtheria toxoid (Vi-DT) conjugate vaccine, potentially offering a valuable new tool in the global effort to control typhoid fever. The most recent estimates suggest that Salmonella enterica serovar Typhi (S Typhi) was responsible for approximately 10 million cases of typhoid fever and the loss of 9·8 million disability-adjusted life-years in 2017. 2 Stanaway JD Reiner RC Blacker BF et al. The global burden of typhoid and paratyphoid fevers: a systematic analysis for the Global Burden of Disease Study 2017. Lancet Infect Dis. 2019; 19: 369-381 Summary Full Text Full Text PDF PubMed Scopus (210) Google Scholar The highest burden of disease is thought to occur in infants and school-age children (ie, those aged 1–14 years), predominantly in south Asia. Effective long-term disease control will require substantial improvements in water quality and sanitation infrastructure, combined with targeted vaccination campaigns. Even though typhoid vaccines have been used for over a century, the past decade has seen substantial progress in the development of safe and effective vaccines against typhoid fever. Although effective, early generation vaccines have limitations that have precluded their widespread programmatic deployment in routine immunisation schedules. Safety and immunogenicity of the Vi-DT typhoid conjugate vaccine in healthy volunteers in Nepal: an observer-blind, active-controlled, randomised, non-inferiority, phase 3 trialWhen administered as a single dose, the Vi-DT test vaccine was safe, immunogenic, and non-inferior to the Vi-TT vaccine at 4 weeks post vaccination. Equivalent immunogenicity of the three lots of Vi-DT vaccine was also shown, supporting the manufacturing process of this vaccine. Once prequalified by WHO, this vaccine could be an option for purchase by UN agencies. Full-Text PDF Open Access