Lot release testing of established vaccines relies on using animal models. Many of these models were developed decades ago and reflect the level of product knowledge, production technology and quality management in those days. Current production techniques are optimised, in-process control is implemented and tight quality management systems are in place. These developments have brought testing for lot-to-lot consistency into reach. The consistency approach involves the use of a set of parameters obtained by using innovative in vitro technologies, to define the product along the manufacturing pathway and to ensure similarity to a lot of proven efficacy and safety. The ambition of the VAC2VAC project is a demonstrated proof of concept of the consistency approach for lot release testing. We will develop/optimise and validate innovative in vitro methods for the categories of established vaccines on the market. Product profiles will be defined using analytical methods, cell-based assays and bioinformatics. The project includes 7 WPs: 4 on R&D, and one each on validation, promotion to regulatory acceptance and consortium management. Consortium partners represent the vaccine stakeholder groups (OMCLs, Academia, Translational research institutes and Vaccinology alliances) and are complementary for the expertise ranging from method development and validation to facilitating and providing guidance to regulatory acceptance. Acceptance will be promoted by strategic guidance activities: a roadmap conference, workshops and training courses. Implementation of the consistency approach in lot release testing has multiple impact: 1) strengthening fundamental understanding of vaccine products resulting in enhanced understanding of vaccine quality 2) strengthening competitiveness of European Vaccine Industries resulting in reduced QC costs and shortened QC time. 3) strengthening European animal welfare policies resulting in a substantial reduction in animal numbers for vaccine QC