Functional activity of antibodies after immunization of Finnish and Israeli infants with an 11-valent pneumococcal conjugate vaccine

Finnish and Israeli infants received an 11-valent mixed carrier pneumococcal conjugate vaccine (11PCV) with or without aluminum adjuvant at the age of 2, 4, 6, and 12 months. We measured opsonophagocytic activity (OPA) of antibodies to pneumococcal strains of serotypes 4, 6B, 14, 19F, and 23F. At 7 months, OPA was clearly detected for all the serotypes. At 13 months, OPAs increased further and the proportion of individuals with a positive OPA ranged between 81 and 100%. The adjuvant improved functional activity of antibodies to serotype 6B pneumococci. In conclusion, immunization of infants with the 11PCV induced functionally active antibodies.