NIBSC performs testing on tetanus vaccine products to ensure compliance with requirements for potency and safety. Traditional potency assays involve challenging animals with toxin to confirm protection after immunisation with vaccine. NIBSC led the European validation studies to replace these traditional challenge methods with an in vitro antibody assay for potency testing of tetanus component in combined vaccines. An alternative potency assay developed at NIBSC is now included in the Ph Eur and introduced for testing of combined vaccine used in the UK childhood immunisation program. In vitro antigen content and degree of adsorption assays have also been developed for improved characterisation of Tetanus toxoids and for monitoring batch to batch consistency.