Varicella vaccine without human serum albumin versus licensed varicella vaccine in children during the second year of life: A randomized, double-blind, non-inferiority trial

GSK’s varicella vaccine contains human serum albumin (HSA) which is used to stabilize the virus and prevent immunogens from adhering to the injection vial walls. However, because HSA is derived from human blood, there is a theoretical risk that it might contain infectious agents which could be unsafe for humans.