Vaccine is also called an immunization. It gives boost to immune system and fight against harmful viruses/bacteria. Vaccine research is a long process. There is no vaccine for HIV. Scientists are working on HIV vaccines in labs and animals it helpful for researchers learn to how will vaccine works. After completion of laboratory work, conducting clinical trials in human health volunteers by sequential phases. Such as phase-I and phase-II provides data how it works against HIV virus to protect Immune system, depends up on this results vaccines are processed in large scale as phase-III trails. This phase-III trails are done in incidence of HIV infection due to scientific reasons.