How effective is vaccination in preventing pneumococcal disease?

Vaccination with a preparation that currently contains 23 pneumococcal capsular polysaccharides (PPV23) successfully reduces the risk of serious pneumococcal infection by an estimated 50% to 80%. Because infants and young children do not respond to polysaccharide antigens, a conjugated polysaccharide vaccine that first contained 7 capsule types (PCV7) and now contains 13 capsule types (PCV13) was developed for use in them. A single study in patients with AIDS showed protection against pneumococcal disease by PCV13, but not after PPV23. Based on these observations, the CDC has now recommended that immunocompromized adults receive PCV13 followed 8 weeks later by PPV23.