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

The 7-valent pneumococcal polysaccharide-protein (CRM(197)) conjugate vaccine (PCV-7) was licensed based on clinical efficacy trials using the four-dose schedule of three infant doses and a booster dose in the second year of life (3 + 1). An assessment of PCV-7 immunogenicity in studies evaluating two infant doses with a booster (2 + 1) showed similar immunogenicity for the 2 + 1 and 3 + 1 schedules, with the exception of lower post-dose two responses for serotypes 6B and 23F, compared with a three-dose primary series. The 2 + 1 PCV-7 schedule has been shown to be effective in controlling pneumococcal disease in several countries, as used in national immunization programs that are marked in particular by good uptake, compliance with the booster dose and application of a catch-up program.