Immunogenicity and safety of a 13-valent pneumococcal conjugate vaccine administered in a prime-boost regimen among Chinese infants: a randomized, double blind phase III clinical trial

This study aimed to evaluate the immunogenicity and safety of a 13-valent pneumococcal conjugate vaccine (PCV13). In total, 1200 infants were randomized into two groups with a 1:1 allocation and received a three-dose series of tested PCV13 or control PCV13 at ages 2, 4 and 6 months, respectively, and a booster dose at 12-15 months. Blood samples were collected before and 30 days after primary and booster vaccination. Serotype-specific antibodies were measured using ELISA for immunoglobulin G (IgG) and OPA for functional antibodies. Safety data were collected for 30 days after each inoculation. Results showed that post primary vaccination seropositive rates of all 13 serotypes except type 3 were not significantly different between two groups. The seropositive rate for type 3 in Group T was significantly higher than Group C (P < .0001). For all 13 serotypes except type 7 F, the GMCs in Group T were significantly higher than Group C. The GMC for type 7 F in Group T (P < .0009) was significantly lower than Group C. The frequencies of overall adverse events (P = .0064) and solicited adverse reactions (P = .0019) in Group T were significantly lower than Group C. Post booster vaccination, seropositive rates for all serotypes in Group T were 100.00%. For all serotypes except type 23 F, IgG GMCs in Group T were significantly higher than Group C. Totally, 21 subjects reported SAEs and all but one were considered irrelevant or probably irrelevant to vaccination. In conclusion, the tested PCV13 showed non-inferior immunogenicity and had a good safety profile compared with control vaccine.