The pneumococcal conjugate vaccine, PCV13, may be better in adults than the pneumococcal polysaccharide vaccine, PPSV23, at reducing disease burden because of its potential effectiveness against nonbacteremic pneumococcal pneumonia, according to a report in the Feb. 22/29 issue of JAMA.
PPSV23 covers 23 serotypes while PCV13 covers only 13. However, PPSV23 doesn’t appear to consistently prevent nonbacteremic pneumococcal pneumonia, while PCV13 is more likely to do so, based on preliminary experience.
Photo (c)Micah Young/iStockphoto.com
"Our analysis favors vaccinating adults with PCV13 instead of PPSV23," chiefly because experts expect that PCV13 will be more effective against nonbacteremic pneumococcal pneumonia than PPSV23 appears to be, the researchers said.
Because nonbacteremic pneumococcal pneumonia is much more common than invasive pneumococcal disease and is responsible for much more morbidity and mortality, PCV13, despite its narrower serotype coverage, should prevent more pneumococcal disease, reported Dr. Kenneth J. Smith of the section of decision sciences and clinical systems management, University of Pittsburgh, and his associates.
The question of which pneumococcal vaccine to use in adults came to the fore when the Food and Drug Administration recently approved the use of PCV13 in patients aged 50 years and older. Dr. Smith and his colleagues used decision statistical modeling techniques to estimate the cost effectiveness of six different possible pneumococcal vaccine strategies in identical hypothetical cohorts of adults aged 50 and older who were tracked as they aged.
The six strategies were no vaccination, the present U.S. Advisory Committee on Immunization Practices recommendation to vaccinate all adults with PPSV23 at age 65, substituting PCV13 for PPSV23 and vaccinating according to the ACIP recommendations, vaccinating with PCV13 at age 50 and with PPSV23 at age 65, vaccinating with PCV13 at ages 50 and 65 years, and vaccinating with PCV13 at ages 50 and 65, then with PPSV23 at age 75.
The models took into consideration the potential effects of herd immunity, different levels of patient risk of contracting pneumococcal disease, different levels of vaccine effectiveness based on patient age and comorbidity, and three different outcomes after pneumococcal infection: death, disability, or recovery.
"Our analysis favors vaccinating adults with PCV13 instead of PPSV23," chiefly because experts expect that PCV13 will be more effective against nonbacteremic pneumococcal pneumonia than PPSV23 appears to be, the researchers said.
Moreover, the data "suggest that PCV13 administered either as a substitute for PPSV23 [according to] current recommendations or [given] routinely at ages 50 and 65 years might reduce pneumococcal disease burden in an economically reasonable fashion," Dr. Smith and his colleagues wrote (JAMA 2012;307:804-12).
According to their models, substituting PCV13 for PPSV23 would cost $28,900 per quality-adjusted life-year, while staying with PPSV23 would cost $34,000 per quality-adjusted life-year. Even giving PCV13 at age 50 and again at age 65, which would cost $45,100 per quality-adjusted life-year, would still be cost effective, they noted.
However, the study results would not hold true if PCV13’s effectiveness against nonbacteremic pneumococcal pneumonia proves to have been overestimated. If it turns out that PCV13 is not very effective against nonbacteremic pneumococcal pneumonia, then the current PPSV23 recommendations would be superior, the investigators said.
Similarly, the results of this study would not hold true if it turns out that childhood vaccination with PCV13, which has only recently begun, substantially changes herd immunity, reducing disease rates in adults.
This study was supported by the National Institute of Allergy and Infectious Diseases. No relevant financial disclosures were reported among the study’s authors.