AS04 (Aka. "Adjuvant System 04") is a trade name for combination of adjuvants used in various vaccine product by GlaxoSmithKline (GSK), in particular the Fendrix Hepatitis B vaccine. It consists of aluminum hydroxide and monophosphoryl lipid A (MPL). Furthermore it is the successor of AS03 which is a Squalene based adjuvant approved for pandemic vaccine by the EMA.
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AS04 Wikipedia(Text) CC BY-SA