Long-term effect of pneumococcal conjugate vaccine on nasopharyngeal colonization by Streptococcus pneumoniae--and associated interactions with Staphylococcus aureus and Haemophilus influenzae colonization--in HIV-Infected and HIV-uninfected children.

After a primary series of 3 doses, it was found that a 9-valent pneumococcal conjugate vaccine no longer reduces nasopharyngeal colonization by vaccine serotypes in children 5.3 years of age. In addition, human immunodeficiency virus (HIV)-infected children (n=81) had a higher prevalence of colonization by Streptococcus pneumoniae and Haemophilus influenzae (71.6% and 74.1%, respectively) than did HIV-uninfected children (n=271; 50.9% and 52.0%, respectively), suggesting that increased colonization may contribute to the greater burden of pneumococcal disease in HIV-infected children. Inverse associations between colonization by S. pneumoniae and colonization by Staphylococcus aureus and between colonization by S. aureus and colonization by H. influenzae were observed only in HIV-uninfected children, possibly as a result of suboptimal adaptive immunity after previous colonization in HIV-infected children.