Pneumococcal vaccination of older adults

Pneumococcal polysaccharide vaccines have demonstrated effectiveness in prevention of invasive pneumococcal disease (IPD). 1 However, their effectiveness against non-invasive pneu-mococcal pneumonia or all-cause community-acquired pneumonia (CAP) has not been established; two recently published meta-analyses concluded that prevention of pneumococcal pneumonia could not be demonstrated for pneumococcal polysaccha-ride vaccines. By contrast, conjugated pneumococcal vaccines have proven effective against pneumococcal pneumonia and all-cause pneumonia in infants and young children. 4-6 This success generated interest in their potential use in adults for the prevention of pneumococcal CAP, which remains a major unmet medical need. Consequently, the United States Food and Drug Administration granted accelerated approval of the 13-valent pneumococcal conjugate vaccine (PCV13) based on immuno-logic non-inferiority to 23-valent pneumococcal polysaccharide vaccine (PPSV23). In their review, Drs Fedson and Guppy note that the immunogenicity of the predecessor 7-valent pneumococ-cal conjugate vaccine was similar to that of PPSV23, but does not describe the results of the pivotal clinical trials that supported the licensure of PCV13 for adults aged 50 y and older. 7 Functional antibody responses to PCV13 were compared with those generated by PPSV23 for the 12 shared serotypes and serotype 6A, unique to PCV13. In subjects not previously vaccinated with PPSV23, functional antibody responses to a single dose of PCV13 were not only similar (noninferior) to responses to PPSV23 for all shared serotypes, but were statistically significantly higher for 9 of the 13 serotypes. 8 This pattern was repeated in adults who had previously received a dose of PPSV23 at least 5 y earlier; functional antibody responses to PCV13 were not only similar (noninferior) to responses to PPSV23 for all shared serotypes but were statistically significantly higher for 11 of the 13 serotypes. 9 Drs Fedson and Guppy also maintain that " repeat vaccination with PPV23 was found to be safe and effective with no evidence of hyporesponsiveness. " In the PCV13 study summarized above, subjects returned for a dose of either PCV13 or PPSV23 3 to 4 y after their initial dose of PCV13 or PPSV23. 10 Prior to the second vaccination, functional antibody levels had declined in all groups. However, a second dose of PCV13 generated functional antibody responses comparable to those seen after the first dose of PCV13 for all of the serotypes and a statistically significantly higher response to the second dose for 6 of the 13 serotypes. A similar result was observed when a dose of PCV13 was …