A phase III randomised, open label clinical trial evaluating the immunogenicity of a 10-valent pneumococcal conjugate vaccine booster compared to the standard 13-valent pneumococcal conjugate vaccine booster given at 12 months of age to healthy children who have received the 13-valent pneumococcal conjugate vaccine at 2 and 4 months of age

INTERVENTION: Blood sampling: Study nurse/doctor at the participants' home. Diary cards: Participants will be asked to record any local/general reactions to vaccine for 4 days after vaccination. In addition any medically significant adverse events occuring between the study visits are to be recorded. All concomitant medication used during this period will also be recorded. Health assessment: Study nurse/doctor at the participants' home. Routine vaccines: MMR‐Hib‐MenC Study vaccine and comparator, Study nurse/doctor at the participants' home Taking oral temperature, Prior to receive the vaccine, oral temperature will be recorded at the CCVTM clinic rooms Study Entry : Single Randomisation only CONDITION: Topic: Medicines for Children Research Network, Primary Care Research Network for England; Subtopic: All Diagnoses, Not Assigned; Disease: All Diseases, All Diseases ; Infections and Infestations ; Streptococcal infection, unspecified site PRIMARY OUTCOME: Not provided at time of registration SECONDARY OUTCOME: Not provided at time of registration INCLUSION CRITERIA: 1. Aged 12 months (2 weeks to +6 weeks) at time of enrolment 2. Have received two doses of PCV13 at less than 6 months of age with a gap of at least 6 weeks between the two vaccinations 3. Have received all primary vaccines according to the UK routine immunisation schedule 4. Available for entire study period and whose parent/legal guardian can be reached by telephone 5. Healthy children as determined by medical history and physical examination, done by a study nurse (and/or study doctor if required, depending on the medical history of the participant and physical assessment), and judgment of the investigator 6. Parent/legal guardian must be able to complete all relevant study procedures during study participation