Preliminarily Evaluation the Safety and Immunogenicity of Tetanus, Reduced Diphtheria and Acellular Pertussis (Five Components) Combined Vaccine, Adsorbed (Tdcp) in Participants Aged 6 Years and above: A Blinded and Randomised, and Controlled Phase I Clinical Trial

Xiaoyu Liu¹Chen Wei²Haitao Huang³Jingxuan Wan³Yajun Li¹Feiyu Wang³Siwen Li¹Ying Wang³Xuewen Wang⁴Xue Wang³Xiuwen Sui³Jinbo Gou³Tao Zhu^3*Xiao Ma^2*Weijun Hu^1*

• ¹Shaanxi Provincial Center for Disease Control and Prevention, Xi'an, Shaanxi Province, China
• ²National Institutes for Food and Drug Control (China), Beijing, Beijing Municipality, China
• ³CanSino Biologics Inc., Tianjin, China
• ⁴Shanghai Imstat medical technology CO., LTD, Shanghai, China

Pertussis remains a significant global public health challenge, particularly in China, where no licensed pertussis-containing vaccines are available for individuals aged 6 years and older. This blind, randomized, and controlled phase I clinical trial evaluated the safety and immunogenicity of the Tetanus, Reduced Diphtheria, and Acellular Pertussis (Five Components) Combined Vaccine, Adsorbed (Tdcp). Participants aged 6 years and above were divided into three age subgroups (6–11, 12–17, and ≥18 years) and randomized to receive Tdcp or control vaccines (PPV23 or DT). Safety endpoints included the incidence of adverse reactions within 30 days post-vaccination, while immunogenicity was assessed through seroconversion rates and geometric mean concentrations (GMCs) of anti-DT, TT, PT, FHA, PRN, and FIM 2&3 antibodies at 30 days post-vaccination. Among 178 participants, the incidence of total adverse reactions in the Tdcp group was 54.62%, primarily local reactions such as pain and itching, with no significant differences compared to controls (p > 0.05). Immunogenicity analysis revealed robust immune responses in the Tdcp groups, with seroconversion rates for pertussis-related antigens exceeding 75% in all age groups. The GMCs for anti-PT antibodies reached 125.60 IU/mL, 150.28 IU/mL, and 131.14 IU/mL in the ≥18 years, 12–17 years, and 6–11 years of Tdcp groups, respectively. Overall, the Tdcp vaccine demonstrated a good safety profile and robust immunogenicity in participants aged 6 years and above. The inclusion of five pertussis antigens, particularly PT, elicited strong immune responses, supporting its potential as an effective booster vaccine for adolescents and adults.