A randomized, open-label, parallel design study to compare the immunogenicity of simultaneous administration versus sequential administration of quadrivalent influenza vaccine and 23-valent pneumococcal polysaccharide vaccine in the elderly

Background: In the 2015/2016 season, the quadrivalent influenza vaccine (QIV) became available in Japan. We evaluated the immunogenicity of simultaneous administration (SIM) of QIV and 23-valent pneumococcal polysaccharide vaccine (PPSV23). Methods: This study was a randomized, non-inferiority, open label trial conducted at a single center in Japan. A total of 162 adults aged ≥65 years were randomly assigned to either the SIM group (received injections of PPSV23 and QIV simultaneously) or sequential administration (SEQ) group (received injection of PPSV23 at 2 weeks post-administration of QIV). Pneumococcal IgG titers of serotype 23F, 3, 4, 6B, 14, and 19A were assessed. This trial was registered with the ClinicalTrials.gov, number NCT02592486. Results: A total of 81 and 76 patients were evaluated in the SIM and SEQ groups, respectively. We found that the response rate of serotype 23F in the SIM group (77.8%) was not inferior to that in the SEQ group (77.6%) (difference, 0.1%; 90% confidence interval, -10.8% to 11.1%). IgG titers at 4–6 weeks after vaccination did not show significant differences between the two groups in all serotypes. H1N1, H3N2, and B Phuket strains of influenza did not show differences in the odds ratios for seroprotection rates between the two groups. No significant differences were found in adverse reactions. The results at 6 month after vaccination will be reported at the congress. Conclusion: The SIM of PPSV23 and QIV showed an acceptable immune response compared to that of SEQ, without an increase of adverse reactions.