Can people with AIDS/HIV be vaccinated?
Yes. Immunization is an important part of the overall treatment strategy for HIV positive individuals. HIV infection is a risk factor for a number of vaccine preventable infectious diseases. Immunization in these patients is particularly important because of their increased risk of developing disease. (See Cecil Medicine Ch 396)
Can the immune system still mount a response to the vaccine?
Yes. HIV infection does lead to a decreased immune response. Though the primary deficiency is a decrease in both CD4+ (helper) T-cell count and function, there is, perhaps consequently, B-cell dysfunction as well. This would suggest that vaccines are less immunogenic. When this is studied directly, as would be expected, we see that vaccines are less immunogenic, but they are still effective.
Which vaccines are given?
Specific recommendations are based on both the age of the individual and their immune status. As a rule, vaccines are more effective when given early in the natural history of an HIV infection or after immune reconstitution with HAART, but there is some effectiveness and little risk of heat killed or subunit only vaccines even in highly immunosuppressed individuals. While live attenuated vaccines are contraindicated in individuals with a CD4+ cell count below 200, these vaccines are given routinely to other HIV positive patients. Current guidelines are found here. Here is the main figure from those guidelines: