To find out if vitamin D supplementing can lead to an improvement in immunological status in HIV-infected children as part of routine clinical care

The objective of this study is to determine the impact of vitamin D on immunological status in HIV-infected children as measured by CD4 count (CD4 percent). We will determine if vitamin D supplementation leads to a measurable change in CD4 count (CD4 percent) in HIV-infected children in the context of routine clinical care.

Specific study questions are:

1. Does vitamin D supplementation lead to a change in CD4 percent (CD4 count) in HIV-infected children?
2. Do the serum levels of the active form of vitamin D [1, 25(OH)2D and 25(OH)D] correlate with CD4 percent (CD4 count) in HIV-infected children?

Inclusion Criteria:

• HIV-infected children as defined by ≥ 2 positive HIV DNA PCRs and/or HIV cultures of blood for children less than 18 months of age, or by positive screening and confirmatory serologic testing in those older than 18 months of age
• Stable HIV disease, defined by the absence of change in HIV clinical or immunologic category during the preceding 6 month period, prior to commencing the study
• Age 3 years through 18 years
• Voluntary informed consent

Exclusion Criteria:

• Any antiretroviral medication change in the 6 months prior to the study, or any anticipated antiretroviral medication change during the duration of the study
• Active participation in another treatment trial
• Serum calcium < 2mmol/L at baseline