Two-in-One Protection: Evaluating the Trivalent Salmonella Polysaccharide Conjugate Vaccine

Article Impact Level: HIGH
Data Quality: STRONG
Summary of Nature Medicine, https://doi.org/10.1038/s41591-025-04003-z 
Dr. Wilbur H. Chen et al.

Points

The novel Trivalent Salmonella Conjugate Vaccine (TSCV) was designed to protect against both typhoidal and non-typhoidal Salmonella serovars prevalent in sub-Saharan Africa.
A randomized, placebo-controlled Phase 1 trial involving 22 healthy adults confirmed that the new TSCV vaccine was safe and well tolerated across both the 6.25-μg and 12.5-μg dose cohorts.
The most frequent solicited adverse event observed in the vaccine recipients was common, short-lived injection site pain, meeting the trial’s prespecified primary safety endpoints.
The vaccine demonstrated outstanding immunogenicity, with all 100% of vaccine recipients showing a ≥4-fold increase in serum IgG against all three polysaccharide components.
The two flagellin components elicited high response rates, reaching 88% and 100% in the lower and higher dose groups respectively, strongly warranting further evaluation of TSCV

Summary

This randomized, placebo-controlled, first-in-human Phase 1 trial evaluated the safety and immunogenicity of a novel Trivalent Salmonella Conjugate Vaccine (TSCV) in a cohort of 22 healthy adults aged 18−45 years. TSCV is designed to protect against both typhoidal and non-typhoidal Salmonella (NTS), prevalent causes of invasive disease in young children in sub-Saharan Africa. Participants were randomly allocated to receive 6.25-μg TSCV (n=8), 12.5-μg TSCV (n=10), or placebo (n=4). The primary and co-primary objectives were the assessment of safety and serum IgG responses, respectively, against the three vaccine polysaccharides and two flagellin carrier proteins.

The TSCV was determined to be safe and well tolerated, successfully meeting the prespecified safety endpoints. The most frequent solicited adverse event reported was transient injection site pain. No hazard ratios or confidence intervals were provided in the abstract but are necessary for a complete risk profile in the full paper.

Immunogenicity analysis revealed robust responses across all vaccine antigens. For each of the three vaccine polysaccharides, immune responses, defined as ≥4-fold increases over baseline, were observed in 100% of vaccinees (both dose groups combined), with 0% of responses in the placebo group, thus meeting the immunogenicity endpoints. The two flagellin carrier proteins demonstrated response rates of 88% (7/8) and 100% (8/8) among the 6.25-μg and 12.5-μg TSCV recipients, respectively, and 0% in placebo recipients. These positive data warrant further clinical evaluation of TSCV against invasive Salmonella disease.

Link to the article: https://www.nature.com/articles/s41591-025-04003-z

References

Chen, W. H., Barnes, R. S., Sikorski, M. J., Datar, R., Sukhavasi, R., Liang, Y., Rapaka, R. R., Pasetti, M. F., Sztein, M. B., Wahid, R., Tennant, S. M., Simon, R., Baliban, S. M., Galen, J. E., Lees, A., Bernshtein, B., Alter, G., Ella, R., Mohan, K., … Levine, M. M. (2025). A combination typhoid and non-typhoidal Salmonella polysaccharide conjugate vaccine in healthy adults: A randomized, placebo-controlled phase 1 trial. Nature Medicine, 1–9. https://doi.org/10.1038/s41591-025-04003-z