Related Experiment Video
Updated: May 8, 2026
Experimental Human Pneumococcal Carriage
Published on: February 15, 2013
Immune response to 13-valent pneumococcal conjugate vaccine with a reduced dosing schedule
Gail L Rodgers1, Susanna Esposito, Nicola Principi
1Pfizer Inc, Collegeville, PA, USA.
Insights
The 13-valent pneumococcal conjugate vaccine (PCV13) shows strong immune responses after two infant doses, supporting its use in a 2+1 schedule. This vaccine offers protection against pneumococcal illnesses, similar to the 7-valent vaccine (PCV7).
Area of Science:
- Immunology
- Vaccinology
- Pediatrics
Background:
- The 7-valent pneumococcal conjugate vaccine (PCV7) is effective in both 3+1 and 2+1 infant schedules.
- The 13-valent pneumococcal conjugate vaccine (PCV13) is approved for a 2+1 schedule in routine immunization.
Purpose of the Study:
- To evaluate the immunologic responses to PCV13 in a 2+1 schedule.
- To assess PCV13 immunogenicity following two doses in a 3+1 schedule.
Main Methods:
- Conducted double-blind, randomized, active-controlled multicenter studies.
- Assessed immunogenicity 1 month post-second infant dose (primary endpoint).
- Measured IgG concentrations, GMCs, OPA, and concomitant vaccine responses.
Main Results:
- PCV13 and PCV7 showed comparable responses for common serotypes after two infant doses.
- PCV13 achieved >85% responders for most serotypes, with lower IgG GMCs for serotypes 6B and 23F post-dose 2.
- All serotypes demonstrated functional activity (>95% OPA ≥ 1:8) and boosted post-toddler dose.
Conclusions:
- PCV13 elicits robust immune responses after two infant doses in a 2+1 schedule.
- These findings support the transition from PCV7 to PCV13 in countries utilizing a 2+1 immunization schedule.
Background:
The 7-valent pneumococcal conjugate vaccine (PCV7) has demonstrated effectiveness against pneumococcal illnesses when administered as 3 infant doses plus a toddler dose (3+1 schedule) or as an abbreviated schedule of 2 infant doses plus a toddler dose (2+1 schedule). The 13-valent pneumococcal conjugate vaccine (PCV13) is approved and World Health Organization-prequalified for administration in a 2+1 schedule when used as part of routine immunization programs.
Objective:
To summarize immunologic responses elicited by PCV13 administered in a 2+1 schedule and following 2 doses in a 3+1 schedule.
Methods:
Studies were double-blind, randomized, active-controlled, multicenter studies except the Mexico study (open-label, single-arm). In 2+1 studies, PCV13 was administered at 2, 4, and 12 (UK) or 3, 5, and 11 (Italy) months. In 3+1 studies (Spain and Mexico), assessment was made postdose 2 of the primary series (2, 4, and 6 months). The primary immunogenicity endpoint was the proportion of participants achieving serotype-specific antipolysaccharide immunoglobulin (Ig)G concentrations ≥ 0.35μg/mL (i.e., responders) 1 month postdose 2. Pneumococcal IgG geometric mean concentrations (GMCs), opsonophagocytic activity (OPA), and concomitant vaccine responses were assessed.
Results:
PCV13 and PCV7 elicited comparable immune responses for the 7 common serotypes after 2 infant doses. The proportion of PCV13 responders postdose 2 was >85% for most of the 7 common and 6 additional serotypes, except common serotypes 6B (27.9-81.4%) and 23F (55.8-77.5%) and additional serotypes 3 (73.8-96.9%) and 6A (79.2-94.4%). Serotypes 6B and 23F elicited lower IgG GMCs postdose 2 compared with other serotypes; all serotypes demonstrated boosting posttoddler dose. All serotypes demonstrated functional activity; >95% of participants achieved OPA levels ≥ 1:8 postdose 2. Concomitant vaccine responses were similar between PCV13 and PCV7 groups.
Conclusion:
Immune responses elicited by PCV13 following 2 infant doses support transition from PCV7 to PCV13 in countries using a 2+1 schedule.
Related Concept Videos
01:51Vaccinations
01:29Hypersensitivity Reactions: Delayed Hypersensitivity Reactions
01:23Immunological Memory
What is Immunological Memory?
Immunological memory is an integral function of the immune system that allows it to recognize and react more rapidly and effectively to pathogens previously encountered. This feature is...
01:19Hypersensitivity Reactions: Immune-Complex Reactions
01:21Vaccines
01:01Dosage Regimen: Fixed Dose
Fixed-dose regimens can be used for various routes of administration, including intravenous (IV) injections and oral medications. For IV administration, a predetermined amount of the drug is...