Brief Report

Conjugate Pneumococcal Vaccine and Adults

By Stan Deresinski, MD, FACP, FIDSA

Clinical Professor of Medicine, Stanford University, Associate Chief of Infectious Diseases, Santa Clara Valley Medical Center

Dr. Deresinski does research for the National Institutes of Health, and is an advisory board member and consultant for Merck. This article originally appeared in the July issue of Infectious Disease Alert.

Synopsis: While Prevnar 13 has received FDA approval for use in adults aged 50 years and older, the CDC recommends continued use of the 23-valent polysaccharide pneumococcal vaccine until further information becomes available.

Source: CDC. Licensure of 13-valent pneumococcal conjugate vaccine for adults aged 50 years and older. MMWR Morb Mortal Wkly Rep 2012;61:394-395.

PREVNAR 13 (PCV13), A 13-VALENT PNEUMOCOCCAL CONJUgate vaccine, which had been available for pediatric use since 2010, was approved at the end of 2011 by the FDA for the prevention of pneumonia and invasive disease caused by serotypes in adults 50 years of age and older. Although not yet recommended by the Advisory Committee on Immunization Practices (ACIP), PCV13 is available for use among adults in this age group.

This approval was not based on a demonstration of protective efficacy but rather on the demonstration of immunogenicity comparable to that observed with the 23-valent pneumocococal vaccine, Pneumovax 23. Confounding this approach is that, while it is agreed that the latter is protective against invasive pneumococcal disease, a consensus regarding its ability to prevent nonbacteremic pneumococcal pneumonia is lacking. Furthermore, the antibody response that correlates with protection remains unknown. PCV13 serotypes currently account for approximately one third of cases of invasive pneumococcal disease among adults aged 65 years and older. In addition, 11 serotypes that account for 25% of invasive pneumococcal disease cases in adults aged 65 years and older are included in PCV23 but not in PCV13. Thus, there remains a degree of uncertainty regarding the efficacy of PCV13 in adults. However, the ability to prevent pneumococcal pneumonia is currently being evaluated in a trial involving 85,000 individuals aged 65 years and older who had never received PPSV23 in the Netherlands.

The availability of PCV13 for adults 50 years of age and older has raised the question of whether clinicians should switch to its use in place of PCV23, not only in the outpatient setting, but also as part of obligatory vaccination of targeted inpatients. The following is the current recommendation: “ACIP will continue to review evidence as it becomes available to guide development of a recommendation regarding routine use of PCV13 in adults aged 50 years and older. In the meantime, health-care providers should continue to administer PPSV23 in accordance with current recommendations.”