Background: The currently recommended single dose of the 23-valent pneumococcal free polysaccharide vaccine (PPSV23) for adults 65 years of age and older does not provide extended protection into older age. This reflects a significant unmet medical need for alternative strategies to protect older adults against pneumococcal infection, which may be met by the 13-valent polysaccharide conjugate vaccine (PCV13). Methods: We performed a randomized, modified double-blind trial in 936 adults aged 70 years and older who had previously received PPSV23 at least 5 years before study entry and were now vaccinated with PCV13 or PPSV23. At 1 year after enrollment, all subjects received a follow-on dose of PCV13. Anti-pneumococcal opsonophagocytic activity (OPA) titers were measured before and at 1 month after each vaccination. Results: Following the enrollment vaccination, OPA titers were significantly greater in the PCV13 group compared to the PPSV23 group for 10 of the 12 serotypes common to both vaccines and to serotype 6A which is unique to PCV13. Responses were noninferior for the other 2 common serotypes. Responses to PCV13 given at 1 year were generally lower in the group that received PPSV23 at enrollment. Conclusion: In adults aged 70 years and older previously vaccinated with PPSV23, PCV13 was significantly more immunogenic than PPSV23 for most of the common serotypes and for serotype 6A. The OPA responses after a follow-on dose of PCV13 one year later indicate that a prior dose of PPSV23, but not PCV13, diminishes the response to the subsequent administration of PCV13.
Bibliographical noteFunding Information:
This study was funded by Wyeth Vaccines Research , which was acquired by Pfizer Inc. in October 2009. The sponsor and all authors were involved in the study design and the data collection, analysis, and interpretation of data, writing of the manuscript and in the decision to submit the manuscript for publication.
AG, TRJ, DAS, EAE, WCG, and BS-T are current employees of Pfizer and may hold stock options. LAJ, KR, KP, and RNG received funding from Pfizer to conduct this study. LAJ received support from Pfizer for attendance at a scientific meeting. The Group Health Research Institute has received grants from Pfizer, Novartis, Inviragen, Sanofi-Pasteur, the National Institutes for Health and the Centers for Disease Control and Prevention. The Minneapolis VA Medical Center was supported in part by the research service of the Minneapolis VA Health Care Service. Uppsala University has received research grants from Pfizer, GlaxoSmithKline, Eurocine and Sanofi-Pasteur. RNG received support from Pfizer for attendance at a scientific meeting. The University of Kentucky was supported in part by an National Institutes for Health research grant to their Aging Center, and has received research grants from Viropharma, T2, PaxVax and Bavarian-Nordic.
- Pneumococcal conjugate vaccine