The use of aluminium in vaccine is as

Adjuvant in Vaccine Sometimes a substance is added to a vaccine to enhance the immune response by degree and/or duration, making it possible to reduce the amount of immunogen per dose or the total number of doses needed to achieve immunity. The commonly used adjuvant are aluminium salts (aluminium hydroxide, aluminium phosphate or potassium aluminium sulfate) which primarily enhance the immune response to proteins. They have been shown to be safe over several decades of use. Rarely, they may cause injection site reactions, including subcutaneous nodules, sterile abscess, granulomatous inflammation or contact hypersensitivity Ref: Park 25th edition Pgno : 111