Pneumococcal conjugate vaccines for adults

Abstract

Pneumococcal polysaccharide vaccines have been recommended for routine use in adults in the US since 1977. The currently approved polysaccharide vaccine (PPV23) contains antigens from 23 of the more than 90 different serotypes of pneumococci. There are conflicting data on its efficacy against invasive infections, but its efficacy against non-bacteremic pneumonia, the most common manifestation of pneumococcal disease in adults, is poor.1–3 Moreover, efficacy of PPV23 declines markedly in persons over the age of 75,2 so older adults, who have both the highest incidence of and the most severe morbidity and mortality from pneumococcal infections, receive the smallest benefit. Therefore, a vaccine that is effective against non-bacteremic pneumonia and is also efficacious in the elderly would be an important advance. Conjugate vaccines might fill this role. Compared with PPV23, the 13-valent pneumococcal conjugate vaccine (PCV13) has superior immunogenicity against some serotypes.3 PCV13 has been approved by the FDA for use in adults. However, the Advisory Committee on Immunization Practices has not yet recommended that PCV13 replace PPV23 for routine use in adults, in part because the incremental benefit of recommending the more expensive PCV13 is unclear. Establishing the efficacy of PCV13 against pneumonia in adults and determining its efficacy in different age and risk groups would help policy makers formulate sound recommendations for use of PCV13.