The study aims to determine the seroprevalence of antibodies against tetanus among healthy people aged 1–59 years old in Shaanxi province. IgG against tetanus in serum samples were detected by ELISA. 6,439 subjects were enrolled. The positive rate (≥0.01 IU/mL) was 84.39% and GMC was 0.03 IU/mL. There were significant differences in positive rates (χ² = 308.944, p < 0.01) and GMC (Z = 5,200,000, p < 0.01) among different age groups. The positive rates (χ² = 304.3, p < 0.01) and GMCs (χ² = 146.417, p < 0.01) showed regional differences. Both full protection rate (≥0.1 IU/mL) (χ² = 36.834, p < 0.01) and GMC (Z = 688,000, p < 0.01) increased with the doses of tetanus-toxoid-containing vaccines (TTCVs) administered. The positive rate (χ² = 54.136, p < 0.01) and GMC (Z = 140,200, p < 0.01) decreased gradually with the time interval after full immunization with TTCVs. The full protection rate (≥0.1 IU/mL) (χ² = 176.201, p < 0.01) and GMC (Z = 629,900, p < 0.01) decreased with the interval (years) since the last dose of TTCVs. There were significant differences in the positive rates and GMCs for different ages, regions, immunization histories of TTCVs, and doses of TTCVs administered. The full protection rate and GMC decreased with the interval following full immunization with TTCVs and the interval since the last dose of TTCVs. The importance of using tetanus booster doses should be emphasized in adolescents and adults.

Frequent healthcare visits increase children's risk of cross-infection. In both routine and emergency settings settings, co-administering vaccines or using combination vaccines can improve coverage, compliance, and timeliness. Vaccination is among the most cost-effective public health measures, with high coverage being critical for success, minimal immune interference, and improved programmatic efficiency. This multicenter, randomized, open-label, non-inferiority phase IV trial extended a prior study (NCT04053010) to evaluate the immunogenicity and safety of co-administering sIPV, DTaP, and HepA-L in healthy Chinese children aged 18 months. Among 600 planned participants, 593 were enrolled and randomized (1:1:1:1) between November 2020 and January 2021: Group 1 (n = 148) received sIPV, DTaP, and HepA-L concomitantly; Groups 2/3/4 (n = 148/148/149) received sIPV, DTaP, or HepA-L separately as comparator controls. Immunogenicity non-inferiority was assessed via adjusted geometric mean ratios (co-ad group vs. sep-ad group per antigen) for poliovirus types I/II/III, DTaP components (DT, TT, PT, FHA), and HepA-L, with a prespecified margin of 0.67 for the 95 % CI lower bound. Antibody titers were assessed at baseline and 30 days post-vaccination: Poliovirus neutralizing antibodies (CPE method; reciprocal ND₅₀ titer), DTaP antibodies (ELISA; IU/mL), HepA-L IgG (electrochemiluminescence immunoassay; IU/L). Safety was monitored for 6 months after vaccination to record any adverse events or serious adverse events. Co-administration demonstrated non-inferior immunogenicity compared to separate administration for all antigens: polio types I (1271.21 vs. 1255.79), II (1915.91 vs. 2076.62), III (2306.41 vs. 2416.62); diphtheria (3.52 vs 3.31 IU/mL), pertussis toxoid (53.87 vs. 64.11 IU/mL); filamentous hemagglutinin (36.02 vs. 35.73 IU/mL), tetanus (9.23 vs 9.08 IU/mL), and hepatitis A (513.24 vs. 439.25 IU/L). Adverse event rates were comparable. Within 30 days post-vaccination, the overall adverse reaction (AR) incidence was higher in the co-administration group (11.49 %) than in Group 4 (4.70 %; P = 0.032) but was comparable to that in Group 2 (9.46 %) and Group 3 (6.08 %). Solicited local reactions occurred at similar rates across groups, with induration and redness being the most frequent. Similarly, fever was the predominant systemic reaction. Most ARs were Grade 1-2 in severity; Grade 3 events were rare (≤1.35 % across groups). No vaccine-related serious adverse events were reported. Simultaneous sIPV+DTaP+HepA-L administration is immunologically non-inferior and exhibits an acceptable safety profile, supporting its potential integration to optimize immunization programs. https://clinicaltrials.gov/study/NCT04636827?cond=NCT04636827&rank=1-ID:NCT04636827.

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, randomised, 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 randomised 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.Clinical trial registration: https://clinicaltrials.gov/, identifier NCT06056050.

Objectives: This randomized, double-blind, active-controlled non-inferiority phase 4 clinical trial was conducted to evaluate the immunogenicity and safety of a 23-valent pneumococcal polysaccharide vaccine (PPSV23) compared to an active comparator vaccine. Methods: Pneumococcal vaccine-naïve participants aged ≥2 years were randomly assigned in a 2:1 ratio to receive a single dose of either the investigational vaccine (n = 1199) or the comparator vaccine (n = 600). Immunogenicity was evaluated at baseline and 30 days post-vaccination by measuring serotype-specific IgG antibodies against all 23 pneumococcal serotypes using enzyme-linked immunosorbent assay. The primary outcome was seroconversion, defined as a ≥two-fold increase in serotype-specific IgG antibody titers at day 30 compared to baseline. Results: At one month post-vaccination, seroconversion rates for each of the 23 serotypes ranged from 59.22% to 95.67% in the treatment group, compared to 59.66% to 94.07% in the control group. Non-inferiority was demonstrated for all serotypes, with the lower bounds of the 95% confidence intervals (95%CI) for rate differences exceeding the predefined −10% margin. Moreover, superiority was observed for 12 serotypes (6B, 23F, 1, 2, 4, 8, 9N, 9V, 11A, 15B, 17F and 18C), as the lower bounds of their 95%CI for rate differences were above 0. Adverse reactions were reported in 236 (19.68%) participants of the investigational group and 118 (19.67%) of the control group within 30 days post-vaccination, with no significant differences between groups. Conclusions: The PPSV23 vaccine administered among individual aged ≥2 years was safe, well tolerated and immunogenic, eliciting an immune response either comparable to or higher than control vaccine. These findings support its use as a safe and effective option for pneumococcal immunization.

Objective: In developing countries, combined vaccine availability remains limited due to economic constraints, healthcare infrastructure, and supply chain challenges. While some imported combined vaccines are available in China, their accessibility is restricted. Co-administration of individual vaccines presents a viable alternative. This study evaluates the immunogenicity and safety of simultaneous sIPV and DTaP administration to support vaccination policies and improve immunization rates.Methods: In this randomized, controlled, open-label, multicenter non-inferiority trial, 702 healthy 3-month-old infants from Shaanxi, Shanxi, and Hebei provinces were enrolled and assigned to three groups: Group 1 (sIPV + DTaP co-administration), Group 2 (sIPV alone), and Group 3 (DTaP alone). Vaccines were administered on a 3-4-5-month schedule. Serum samples were collected pre-vaccination and 30 days post-vaccination to assess antibody responses. Adverse events (AEs) were monitored for safety evaluation.Results: Among 671 infants completing the study (642 per protocol), co-administration (Group 1) demonstrated non-inferior immunogenicity compared to separate administration. Seroconversion rates and geometric mean titers (GMTs) for poliovirus types 1,2 and 3 were comparable between Groups 1 and 2. For anti-PT, FHA, D, T, Group 1 showed non-inferiority to Group 3 in seroconversion. However, anti-PT and anti-FHA geometric mean concentrations (GMCs) were lower (Group 1:anti-PT 31.06 [95% CI: 28.56–33.77], anti-FHA 29.40 [27.68–31.24]; Group 3: anti-PT 39.32 [36.25–42.65], anti-FHA 33.06 [31.01–35.24]). No significant differences were observed in anti-D and anti-T GMCs. AE rates were similar across groups, with local reactions (e.g., induration) more frequent in Group 1 (6.84%) than in Group 2 (0.85%). Systemic AEs (primarily grade 1–2 fever) did not differ significantly.Conclusion: Co-administration of sIPV and DTaP is immunogenically non-inferior to separate administration and demonstrates comparable safety. This strategy is feasible and may support simplified immunization schedules in China.Clinical trial registration: ClinicalTrials.gov, identifier NCT04053010.

Objectives: A randomized, double-blind, active-controlled noninferiority phase 4 clinical trial was conducted to evaluate the immunogenicity and safety of a 23-valent pneumococcal polysaccharide vaccine (PPV23). Methods: Pneumococcal vaccine-naïve participants aged ≥2 years were randomly assigned in a 2:1 ratio to receive a single dose of either the treatment vaccine (n=1199) or a comparator vaccine (n=600). We evaluated the immunogenicity before and 30 days post-vaccination, by measuring serum IgG serotype-specific pneumococcal antibodies to 23 serotypes contained in the vaccines via an enzyme-linked immunosorbent assay. The primary outcome was seroconversion (two-fold increase) of serum IgG serotype-specific antibodies at days 30 compared with baseline. Results: One month after the administration of PPV23, seroconversion rates for each of the 23 serotypes ranged from 59.22% to 95.67% in the treatment group, and in the control group from 59.66% to 94.07%. The lower bound of the 95% confidence interval (95%CI) of the rate differences for the 23 serotypes were all larger than −10%. Moreover, 12 serotypes (6B, 23F, 1, 2, 4, 8, 9N, 9V, 11A, 15B, 17F and 18C) had a lower bound of 95%CI for rate difference larger than 0. In total, 236 (19.68%) participants in the treatment group and 118 (19.67%) in the control group reported adverse reactions within 30 days poste-vaccination. No significant differences in incidence of adverse reactions were found between the two comparison groups. Conclusions: The PPV23 vaccine administered among individual aged ≥2 years was safe, well tolerated and immunogenic, eliciting immune response either comparable to or higher than control vaccine.