Pneumococcal polysaccharide-protein CRM197 conjugate vaccines, 7- or 9-valent, in the 2 + 1 schedule

Area of Science:

• Pediatric Vaccinology
• Immunology
• Public Health

Background:

• The 7-valent pneumococcal polysaccharide-protein conjugate vaccine (PCV-7) was initially licensed using a 3+1 dose schedule.
• National immunization programs are increasingly evaluating alternative vaccination schedules for improved efficiency and uptake.

Purpose of the Study:

• To assess the immunogenicity of a 2+1 dose schedule for PCV-7 compared to the traditional 3+1 schedule.
• To evaluate the effectiveness of the 2+1 PCV-7 schedule in real-world national immunization programs.

Main Methods:

• Comparative immunogenicity studies evaluating two infant doses followed by a booster (2+1) versus three infant doses followed by a booster (3+1).
• Analysis of national immunization program data assessing vaccine uptake, booster dose compliance, and catch-up program application for the 2+1 schedule.

Main Results:

• The 2+1 schedule demonstrated comparable overall immunogenicity to the 3+1 schedule.
• Slightly lower post-dose two antibody responses were observed for serotypes 6B and 23F with the 2+1 schedule compared to the three-dose primary series.
• The 2+1 PCV-7 schedule has proven effective in controlling pneumococcal disease in countries implementing it.

Conclusions:

• The 2+1 PCV-7 schedule is a viable and effective alternative to the 3+1 schedule.
• Successful implementation in national programs indicates good vaccine uptake and compliance, supporting its use for pneumococcal disease control.