Question: Some of the physicians I work with are reluctant to administer 23-valent pneumococcal polysaccharide vaccine (PPSV23) to adults, stating that it is not very effective. What do I tell them?
Answer: Invasive pneumococcal disease (IPD) continues to be a major cause of morbidity and mortality in the United States. The Advisory Committee on Immunization Practices (ACIP) has recently published updated recommendations for the prevention of IPD in adults.1 This update adds patients with asthma and smokers to the list of high-risk groups needing vaccination.
The current vaccine (PPSV23) has been available since 1983, when it replaced a 14-valent vaccine that was licensed in 1977. It contains 23 antigen serotypes (1, 2, 3, 4, 5, 6B, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15B, 17F, 18C, 19F, 19A, 20, 22F, 23F, and 33F). In 1997, the recommendations stated that these serotypes caused 85–90% of invasive pneumococcal infections among children and adults.2 The efficacy of PPSV23, as described in Morbidity and Mortality Weekly Report (MMWR), ranges widely depending on the studies (50–80% for prevention of IPD among immunocompetent older adults and adults with underling illness). Other studies cited include overall efficacies of 74% (95% CI 56–85%), 52% (39–63%), and 10% (–77% to 54%) (see MMWR for references). Also see Ask the Experts: Revaccination with 23-valent pneumococcal vaccine on the pharmacist.com Pharmacist Immunization Center.
In a recent case–control study from Spain, 88 patients older than 60 years with laboratory-confirmed IPD were compared with 176 control patients.3 The authors found that PPSV23 had an adjusted effectiveness of 72% in all IPD and 77% effectiveness in vaccine-type IPD.
A prospective, randomized, placebo-controlled, double-blind study from Japan was published recently.4 The investigators looked at vaccine effectiveness in 1,006 patients in 23 nursing homes randomized to receive either PPSV23 or placebo. Pneumococcal pneumonia developed in 14 vaccine patients (2.8%) compared with 37 patients (7.3%) in the placebo group. Death from pneumococcal pneumonia occurred in 13 of 37 patients (35.1%) in the placebo group and no patients in the vaccine group. All-cause pneumonia, as well as pneumococcal pneumonia, also was more common in the placebo group.
Another prospective cohort study looked at the effectiveness of dual influenza and pneumococcal vaccination in outpatient clinics in Hong Kong, China.5 A total of 36,636 patients older than 64 years were given both vaccines (n = 7,292), influenza vaccine alone (2,076), pneumococcal vaccine alone (1,875), or no vaccine (25,393). A 35% reduction in death resulting from cardiovascular or respiratory causes was seen in the dual-vaccinated group compared with the unvaccinated group. This reduction was less in the group receiving influenza vaccination alone (22%). A reduction in hospitalization resulting from the same causes also was seen in the vaccinated groups, with a 58% decrease in pneumococcal pneumonia in the dual-vaccine group.
Circulating serotypes have changed during the previous few years, most likely because of routine use of seven-valent pneumococcal conjugate vaccine (PCV7). The introduction of PCV13 this year will add coverage of additional serotypes in the childhood series. The strains in PCV13 are all included in PPSV23, with the exception of 6A. It has been suggested that these vaccines have a herd effect in protecting unvaccinated patients of all ages. In addition, studies are occurring to determine whether administering PCV13 to older adults can add more protection.
Although PPSV23 is not a perfect vaccine, and the search for more effective vaccines continues, it still reduces illness and death from pneumococcal disease. Vaccination rates continue to be low, particularly in individuals aged 19–64 years (17.1% vaccinated of those indicated) and those 65 years or older (60.6%).6 We need to do better.
Stephan L. Foster, PharmD, FAPhA
Professor and Vice Chair
University of Tennessee College of Pharmacy
APhA Liaison Representative to the Advisory Committee on Immunization Practices (ACIP)
College of Pharmacy
University of Tennessee Health Sciences Center