Pneumococcal vaccination in adults: does it really work?

The universal burden of pneumococcal disease is high. As pneumococcal capsular antigens induce serotype specific antibodies, both the available vaccines (polysaccharide and polysaccharide conjugated) are able to produce serological response. However, there is reasonable skepticism about the effectiveness and efficacy of the 23-valent polysaccharide vaccine, especially in the elderly and in immunocompromised adults. Results from numerous studies are conflicting but the more recent data suggest that polysaccharide vaccine raises inadequate protection against non-bacteremic pneumonia, while the benefit against invasive pneumococcal disease in high-risk population is uncertain. On the contrary, conjugate vaccine, -originally indicated only for infants and young children- appears to be highly effective but it does not cover the tremendous diversity of pneumococcal serotypes being able to cause disease in adults. Despite this, there is growing evidence that conjugate vaccines, due to their superior immunogenicity, could also be offered for adult vaccination, but still there are certain issues that warrant further investigation.