Standardization of the methods and reference materials used to assess virus content in varicella vaccines

Background In Korea, every vaccine lot is tested by the National Center for Lot Release (NCLR) in accordance with the national lot release procedures to ensure the safety and efficacy of vaccines. These quality tests examine the virus content in varicella vaccines via plaque assays (either the agar overlay method [AOM] or plaque staining method [PSM]), according to the procedures suggested by the Korean Reference Material for the Varicella Vaccine (KRMVV) or the manufacturer’s standard in-house protocol.