Antibody response of pneumococcal vaccine: need for booster dosing?

The approved pneumococcal vaccine comprises purified capsular polysaccharide of 23 stereotypes that account for more than 90% of the invasive pneumococcal infections in the USA. It induces adequate anti-polysaccharide IgG antibody levels to most or all of the component polysaccharide antigens in immunocompetent adults. Elderly adults respond about equally well to vaccination as do younger adults. Pneumococcal antibody declines over time, often below 1 month post-vaccination levels, and sometimes about to pre-primary vaccination levels. Second doses of vaccine satisfactorily boost antibody levels in healthy adults, but not in immunocompromised adults or children. The rate of antibody decline differs for the differing capsular stereotypes. In time, pneumococcal antibody wanes in all healthy persons perhaps increasing their risk of serious pneumococcal disease. Elderly and high risk persons face the highest risk of death from invasive pneumococcal disease, supporting the proposition that for these groups revaccination with pneumococcal vaccine at regular intervals may provide the needed increased measure of protection.