Recent advances in pneumococcal vaccination of children.

Pneumococcal disease is a major cause of childhood morbidity and mortality worldwide. However, there is a lack of epidemiological data to describe the vaccine-preventable burden of disease. New pneumococcal conjugate vaccines offer hope of preventing infant pneumococcal disease. The efficacy of the 7- and 9-valent pneumococcal conjugate vaccine (PCV) against invasive vaccine-type pneumococcal disease in young children is between 77 and 97%. The PCV vaccine efficacy against radiological pneumonia in HIV-negative infants for the 7- or 9-valent PCV is 23-30%. The vaccine efficacy in HIV-positive infants is lower--65% against invasive vaccine-type pneumococcal disease and no significant efficacy against radiological pneumonia. The 7-valent PCV showed modest efficacy against acute otitis media (7%) but seems to be more effective in preventing recurrent or severe disease. The high cost of these new vaccines is a barrier to their widespread introduction. The development of other pneumococcal vaccine candidates with wider serotype coverage should be encouraged. These vaccines should be affordable for all countries, particularly those with the highest burden of disease. In addition, other vaccination strategies such as maternal and neonatal immunisation and combinations of fewer doses of the PCV combined with an early dose of the cheaper pneumococcal polysaccharide vaccine need to be assessed further.