The purpose of this study is to learn about the safety of the 20-valent pneumococcal conjugate vaccine (20vPnC) among adults, children, and infants, as well as the immunogenicity of 20vPnC among infants and children under 2 years of age in China. This vaccine will be given as per the age-specific dosing schedules among healthy adults, children and infants in China. This study is seeking healthy participants of 6 groups: * Group 1: Adults ≥18 to \<50 years of age * Group 2: Children ≥2 to \<6 years of age * Group 3: Children ≥12 months to \<2 years of age * Group 4: Infants ≥7 to \<12 months of age * Group 5: Infants ≥42 to ≤98 days of age * Group 6: Infants ≥42 to ≤98 days of age All participants in Group 1 to 5, in this study will receive 20vPnC as per the age-specific dosing schedules: * Group 1: participants will receive 1 dose of 20vPnC. * Group 2: participants will receive 1 dose of 20vPnC. * Group 3: participants will receive 2 doses of 20vPnC. Dose 2 will be given 56 to 70 days after Dose 1. * Group 4: participants will receive 3 doses of 20vPnC. Dose 2 will be given 28 to 56 days after Dose 1, and Dose 3 will be given at 365 to \<455 days of age and at least 56 days after Dose 2. * Group 5: participants will receive 4 doses of 20vPnC. Dose 2 will be given 42 to 63 days after Dose 1, and Dose 3 should be given 42 to 63 days after Dose 2, and Dose 4 should be given at 365 to \<455 days of age. Participants in Group 6 will be randomized in a 1:1 ratio to received either 20vPnC or 13vPnC: \- Group 6: participants will receive 4 doses of 20vPnC or 13vPnC. Dose 2 will be given 42 to 63 days after Dose 1, and Dose 3 should be given 42 to 63 days after Dose 2, and Dose 4 should be given at 365 to \<455 days of age. The study will look at the experiences of people receiving the study vaccine. The study will also look at the immune response of some people receiving the study vaccine. This will help decide if the study vaccine is safe. The total duration of taking part in the study from each group is: * Participants in Group 1 and Group 2 will take part for about 6 months, with 6 visits. * Participants in Group 3 will take part for about 8 months, with 9 visits. * Participants in Group 4 will take part for about 12 months, with 8 visits. * Participants in Group 5 and 6 will take part for about 16 to 19 months, with 11 visits.