The purpose of this study is to evaluate the immunogenicity and safety of 7 - valent pneumococcal conjugated vaccine in HIV - infected children, and assess the predictive factors for protective antibody responses after receiving the vaccine.

S. pneumoniae is an important cause of severe invasive bacterial disease in human immunodeficiency disease (HIV) infected children. The incidence of pneumococcal bacteremia cases requiring hospitalization among Thai children aged < 5 years had a range of 10.6-28.9 cases per 100,000 persons.[1]

Children infected with HIV have a markedly increased risk for pneumococcal infection compared with those who are not HIV-infected. HIV-infected children had rates of invasive pneumococcal disease (IPD) that were 2.8 and 12.6 times the rate among HIV-negative children aged <5 and <3 years, respectively. Incidence of IPD is 6.1 cases/100 patient-years among HIV-infected children through age 7 years [2]

Recent important strategy in prevention of invasive pneumococcal disease (IPD) is an implementation of pneumococcal conjugate vaccine (PCV), which can induce immunity starting from 2 months of age. In a small study of 5-valent PCV among children < 2 years of age, serotype-specific IgG antibodies (ELISA) response after 3 doses was found to be immunogenic among both groups.[3] The Pediatric AIDS Clinical Trials Group Study 292 show that the immunologic responses to 7- valent PCV were similar for all serotypes among asymptomatic and symptomatic HIV - infected children.[4] The study of quantitative and qualitative antibody responses to 9 - valent PCV in HIV-infected children in South Africa shows similar quantitative antibody responses but poorer qualitative antibody responses to the pneumococcal conjugate vaccine when compared to HIV-negative children.[5].

In Thailand, 7 - valent PCV (Prevnar® ) was available in 2003. It is recommended for young children and highly recommended for high risk children such as HIV-infected children, congenital heart disease or premature infants. However, one of the major obstacles for large scale implementation is cost issue. There is no previous study about immunogenicity, safety or efficacy of 7 - valent PCV in HIV -infected Thai children, the objective of this study is to assess the safety and immunogenicity of a 7 - valent PCV vaccine among HIV - infected compared with HIV - exposed children.

Inclusion Criteria:

1. HIV - infected children

   • HIV infected individuals
   • Age between 2 months to 9 years
   • Signed written informed consent

2. HIV - exposed negative children

   • Maternal HIV infection, documented prior to delivery.
   • Age between 2 months to 9 years
   • Signed written informed consent

Exclusion Criteria:

• Active opportunistic infection
• History of hypersensitivity to pneumococcal conjugate vaccine or diphtheria toxoid
• Using oral steroid or immunosuppressive drugs
• Received pneumococcal conjugate vaccine, or pnuemococal polysaccharide vaccine