Lessons learned from recent randomized controlled trials comparing the immunogenicity of different infant vaccination schedules of pneumococcal conjugate vaccine

Abstract

Background: The technically complex pneumococcal conjugate vaccine (PCV) is arguably one of the most important and widely studied vaccines since the Hib vaccine. Given the complexity of its design, the cost of administering the PCV is tremendous. While we cannot make adjustments to the vaccine itself post licensure, we can manipulate the dosing schedule. And yet little work has been done to understand the differences in immune responses across different dosing schedules. Methods: Accordingly, we conducted a review of three recently published randomized control trials that compared immune responses across commonly used vaccine schedules in both high- and low-income countries. Results: Each of these studies assessed how changes to the number of doses, spacing between doses and the use/timing of a booster dose affected ELISA geometric mean concentrations post-primary and post-booster dose. If the goal is to administer vaccinations in the most immunologically efficient manner as possible, evidence from these studies would suggest that several commonly used vaccine schedules are missing the mark. Conclusions: In order to deliver the most “bang for its buck”, PCV dosing schedules should not only leverage convenience but also immunological data. Without the reexamination of PCV schedules the status quo will remain inefficient, ineffective and needlessly expensive, threatening the sustainability of its implementation long-term.