Assessment of functional antibacterial opsonophagocytic antibodies elicited by 13-valent pneumococcal conjugate vaccine administered concomitantly with trivalent influenza vaccine in a randomized clinical trial in adults aged ≥65 years

A randomized, double-blind clinical trial compared immune responses elicited by concomitant administration of 13-valent pneumococcal conjugate vaccine (PCV13) and trivalent inactivated influenza vaccine (PCV13 + TIV), with PCV13 given 1 month after TIV, in healthy, pneumococcal vaccine-naïve adults aged ≥65 years. Serotype-specific pneumococcal anti-polysaccharide IgG antibody concentrations 1-month post-vaccination were uniformly lower after PCV13 + TIV, than after PCV13 alone (Vaccine 2011;29:5195–202). Therefore, post hoc analyses to evaluate the functional antibody titers at 1-month post-vaccination, as measured by opsonophagocytic activity (OPA) assays, were performed. The anti-pneumococcal functional responses, while also generally lower after vaccine co-administration, nonetheless showed a greater degree of similarity between the two vaccine groups than was apparent from the anti-polysaccharide antibody responses. In particular, the proportion of OPA responders after PCV13 and TIV co-administration was similar to that observed after PCV13 alone for all serotypes evaluated. Concomitant use of PCV13 and TIV should therefore be guided by clinical circumstances.