Triptych of the Hermit Saints: pneumococcal polysaccharide vaccines for the elderly

Abstract

Pneumococcal pneumonia is a serious disease with considerable morbidity and mortality in the elderly. Despite adequate antibiotic treatment, the long-term mortality of pneumococcal pneumonia remains high. Preventive measures in the form of vaccination, therefore, are warranted. Twenty-three-valent polysaccharide vaccines have a broad coverage but limited efficacy. Pneumococcal conjugate vaccines have been shown in children to be able to prevent invasive and mucosal pneumococcal diseases. It should be realized that the serotype composition of current pneumococcal conjugate vaccines is not tailored for the elderly, and that replacement disease can occur. Yet, the current 13-valent conjugate vaccine has been shown to protect against infections with vaccine serotypes. Long-term mortality of pneumococcal pneumonia should be included in policy making about the introduction of these vaccines for the elderly.

Keywords: Streptococcus pneumoniae; conjugate vaccines; cost-effectiveness; elderly; pneumonia; vaccination.

Figure 1

Microbiological etiology of CAP. A total of 349 CAP patients from 2 clinical trials were enrolled. Conventional microbiological analysis (blood culture, urinalysis, and sputum culture) identified Streptococcus pneumoniae as a causative organism. Determination of serotype-specific antibodies in serum showed S. pneumoniae involvement in an additional 28% of patients. Most commonly identified pathogens in the other pathogens category were Coxiella burnetti, Legionella species, Mycoplasma pneumoniae, Haemophilus influenzae, Chlamydophila psittaci, influenza A virus, and Staphylococcus aureus. Data from van Mens et al. Abbreviation: CAP, community-acquired pneumonia.

Figure 2

Pneumococcal serotypes and pneumococcal vaccines. Notes: The first generation of pneumococcal conjugate vaccines (PCV7) consists of the serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F. The second generation is PCV10 (PCV7 serotypes + 1, 5, 7F) and PCV13 (PCV10 serotypes + 3, 6A, 19A). Related serotypes belong to serogroups included in the conjugate vaccines. The size of the serotype circles is proportional to the frequency in invasive pneumococcal diseases in the Netherlands before the introduction of pneumococcal conjugate vaccination. Data from Rodenburg et al.

Figure 3

Detail of the right panel of The Triptych of the Hermit Saints by Hieronymus Bosch (1493), Gallerie dell’Accademia, Venice, Italy. Note: Reprinted from Wikimedia Commons.