The mutual effects on safety and immunogenicity of combined vaccination with 15-valent pneumococcal conjugate vaccine and adsorbed acellular DPT in 3-month healthy infants: A randomized, open-label, controlled, phase III clinical trial

To evaluate the mutual effects on safety and immunogenicity of the combined vaccination of the 15-valent pneumococcal conjugate vaccine (PCV15) and the adsorbed acellular diphtheria-tetanus-pertussis combined vaccine (DTaP) in healthy infants aged 3 months (90 to 119 d) old. This phase III clinical trial enrolled 1110 subjects in Tangxian and Yutian County, Hebei Province, China. The total population was randomly divided into three groups on average: 370 infants received coadministration of PCV15 and DTaP at different sites (P+DTP group), 370 infants were vaccinated with PCV15 followed by DTaP after a 7-day interval (with a + 15-day window period) (P-DTP group), 370 infants were vaccinated with DTaP alone (DTap group). These 1110 subjects received the vaccine according to a 3-dose schedule of 0, 1, and 2 months. The antibody seropositivity rate, seroconversion rate, GMC, and the fold increase in GMC were reported for PCV15 and DTaP. The adverse events (AEs) within 30 minutes, solicited AEs from day 0 to day 30, unsolicited AEs from day 0 to day 30 after each dose were reported. Serious adverse events (SAEs) until 6 months after the whole dose were reported. The results showed that seroconversion rates and GMCs of DTaP in the P+DTP group were non-inferior to DTaP group. There was no significant difference in the positivity rate of IgG antibody between the P+DTP group and the P-DTP group. Except some serotypes (serotype 5, 6A, 6B, 9V, 12F, 23F), the differences in IgG antibody seroconversion rate between P+DTP group and P-DTP group were not statistically significant. Incidence of AEs in P+DTP group was lower than P-DTP group and slightly higher than DTaP group. Co-administration of PCV15 and DTaP showed no obvious interaction in this study.