A single-center, randomized, double-blind, positive-controlled, phase IV clinical trial to assess the immunogenicity and safety of adsorbed tetanus toxoid vaccine in individuals aged ≥16 years.

BACKGROUND

Tetanus prevention is effectively managed in infants and young children, yet there remains a need for enhanced measures to improve tetanus prevention among adults.

METHODS

This phase IV, single-center, randomized, double-blind, positive-controlled trial evaluated an adsorbed tetanus vaccine in individuals aged ≥ 16 years, stratified into 16-18 years, 19-49 years, and ≥ 50 years cohorts.

RESULTS

Pre-vaccination seroprotection rates (SPR, ≥0.1 IU/mL) demonstrated age-dependent declines (44.00 %→18.47 %→5.38 %), paralleled by decreasing geometric mean concentrations (GMC: 0.079 IU/mL → 0.052 IU/mL → 0.033 IU/mL). A single booster dose achieved universal seroprotection (100 % SPR) and near-complete seroconversion (SCR ≥ 99.48 %) across all groups, elevating GMCs to 6.831 IU/mL (16-18 years), 3.400 IU/mL (19-49 years), and 1.430 IU/mL (≥50 years), while two doses in the ≥ 50 years cohort further increased GMC to 2.938 IU/mL with 100 % SCR. The vaccine exhibited a favorable safety profile, with mild vaccination-site pain (7.2 %) and pruritus (4.2 %) as predominant reactions, no vaccine-related serious adverse events, and self-limiting systemic effects (pyrexia: 1.6 %; myalgia: 1.2 %).

CONCLUSION

These results confirm robust immunogenicity and safety in adults, supporting tailored booster strategies for aging populations with waning immunity.