PCV13 Vaccine Proves Cost-Effective

Laura Newman, MA

February 21, 2012

February 21, 2012 — The 13-valent pneumococcal vaccine (PCV13) is more cost-effective than the widely used 23-valent pneumococcal polysaccharide vaccine (PPSV23) in adult cohorts aged 50 years and older, according to Markov model analysis reported in the February 22/29 issue of JAMA. However, the analysis is built on assumptions about the effectiveness of the vaccine against nonbacteremic pneumococcal pneumonia (NPP). A clinical trial to evaluate that question is currently underway, but will not be completed until 2013.

"Our analysis favors vaccinating adults with PCV13 instead of PPSV23 and suggests that PCV13 administered either as a substitute for PPSV23 in current recommendations or routine at ages 50 and 65 years might reduce pneumococcal disease burden in an economically reasonable," write Kenneth J. Smith, MD, from the University of Pittsburgh School of Medicine in Pennsylvania, and colleagues.

The investigators modeled pneumococcal disease risk, using 6 vaccine strategies in a series of hypothetical cohorts aged 50 years and older:

  1. no vaccine,

  2. the current Advisory Committee on Immunization Practices (ACIP) adult recommendations (suggesting all persons get vaccinated at age 65 years, or earlier when comorbidities are present, and repeated at age 65 years or older when 5 years have elapsed since the first dose),

  3. using PCV13 instead of PPSV23 at recommended ACIP intervals,

  4. administering PCV13 at age 50 years and PPSV23 at age 65 years,

  5. administering PCV13 at age 50 years and 65 years, or

  6. administering PCV13 at age 50 years and 65 years, followed by PPSV23 at age 75 years.

Patients were tracked as they aged until they died, assuming specific levels of effectiveness under varying vaccine scenarios. To derive risk, 6 factors were multiplied: the baseline probability of infection, herd immunity, the relative likelihood of infection from a vaccine serotype (before PCV13), the projected change in infection serotype likelihood, the probability of being vaccinated, and the probability of vaccine effectiveness. Vaccine costs were estimated at $0.03 per dose, based on the 2006 Healthcare Cost and Utilization Project estimates of vaccine, cost, and adverse event costs.

Of 4.3 million US 50-year-olds in 2006, the model predicted that without vaccination, during their lifetimes, there would be 396,087 NPP hospitalizations, 36,576 invasive pneumococcal disease cases, and 75,647 pneumococcal-related deaths. Because the exact effectiveness against NPP is not yet known, the researchers also tested a worst-case scenario. However, even with the worst-case NPP scenario, using PCV13 as part of the vaccine strategy avoided more pneumonia cases and pneumonia-related deaths than the current ACIP pneumonia vaccine strategy of PPSV23.

If PCV13 replaced PPSV23 in current vaccine recommendations, it would cost $28,900 per quality-adjusted life-year (QALY) gained, which compares favorably with $34,600 per QALY gained with PPSV23. Giving PCV13 routinely at age 50 years, and again at age 65 years, is more costly ($45,100 per QALY), but remains within generally accepted limits for public health expenditures.

In an accompanying editorial, Eugene D. Shapiro, MD, from the Department of Pediatrics, Epidemiology, and Investigative Medicine, Yale University School of Medicine, New Haven, Connecticut, points out key limitations of the cost-effectiveness analysis. "Although the results of the cost-effectiveness analysis...are robust for most variables in the model, the findings are vulnerable to estimates of 2 key parameters about which there is still considerable uncertainty," he writes.

Dr. Shapiro worries about the effect of not knowing the effectiveness of PCV13 on NPP. In addition, PCV13 protects against fewer serotypes than PPSV23, and there is little information as to whether routine adoption of PCV13 would increase the risk of infection by serotypes not included in the vaccine.

Those concerns aside Dr. Shapiro acknowledges that cost-effectiveness studies help to sort out changes in vaccine policy. "What does seem clear is that improvements in vaccines against pneumococci and increased rates of immunization likely will result in continued reductions in the incidence of infections due to this common pathogen," he concludes.

The study was supported by the National Institute of Allergy and Infectious Disease, National Institutes of Health. Two of the study authors disclosed potential conflicts of interest with Merck. The other study authors and Dr. Shapiro have disclosed no relevant financial relationships.

JAMA. 2012;307:804-812, 847-849. Article abstract, Editorial extract

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