Safety and immunogenicity of a new 13-valent pneumococcal conjugate vaccine versus a licensed 7-valent pneumococcal conjugate vaccine: a study protocol of a randomised non-inferiority trial in China

Introduction: The invasive pneumococcal diseases (IPDs) caused by Streptococcus pneumoniae pose an enormous threat to children under 5 years of age. However, routine use of pneumococcal conjugate vaccines could aid in reducing the incidence of IPDs. The purpose of this clinical trial is to assess the noninferiority of the investigational 13-valent pneumococcal conjugate vaccine (PCV13) to the currently licensed 7-valent pneumococcal conjugate vaccine (PCV7). Methods and analysis: 1040 infants will receive a three-dose series of either PCV13 or PCV7 at ages 3, 4 and 5 months, respectively, and a booster dose at 12-15 months. Primary end points are the percentage of participants reaching a serotype-specific IgG concentration of >= 0.35 mu g/mL and the IgG antibody geometric mean concentrations (GMCs) measured 30 days after the primary immunisation. Secondary end points include the percentage of vaccine recipients reaching a serotype-specific IgG concentration threshold of 1.0 mu g/mL, the percentage of participants reaching the pneumococcal opsonophagocytic assay (OPA) titre threshold of 1: 8, and the geometric mean titres (GMTs) of OPA measured 30 days after primary and booster doses. The number of standard IgG responders and IgG GMCs measured 30 days after the booster immunisation will also be determined. To evaluate differences between two groups, the sequential testing of the non-inferiority of PCV13 for the seven common serotypes and its effectiveness in treating the six additional serotypes will be performed. Ethics and dissemination: Ethics approvals have been granted by the Ethics Committees at the three provinces involved in this study: Shanxi, Henan and Hebei. The trial will be reported in accordance with the CONSORT guidance.