Container Closure Integrity Testing (CCIT) is an assay that evaluates the adequacy of container closure systems to maintain a sterile barrier against potential contaminants. Contaminants that could potentially cross a container closure barrier include microorganisms, reactive gases, and other substances (USP <1207>). Container closure systems should maintain the sterility and product quality of sterile final pharmaceutical, biological, and vaccine products throughout their shelf-life. Container closure systems consist of primary packaging components and secondary packaging components (USP <1207>). Primary packaging components are those components that come into direct contact with the product, such as a glass vial or syringe. While, secondary packaging components are those components that are vital to ensure correct package assembly, such as aluminum caps over stoppers (USP <1207>). Container closure integrity testing can be performed in many different ways. All of the testing methods have pros and cons. In addition, some containers, such as ampoules, require 100% integrity testing. Contract Container Integrity Testing laboratories offer numerous state- of-the-art options for leak testing and assessing pharmaceutical package integrity per USP <1207>. Container Closure Integrity test programs have been successfully used to optimize sealing parameters, evaluate container storage temperature impact, replace sterility tests for product stability batches, screen production lots for faulty packages and support regulatory submission applications for product commercialization around the world. The Vacuum Decay method is a non-destructive and quantitative assay (USP <1207.2>). It detects leaks in nonporous, rigid or flexible packages. Packages with a porous component can be tested by masking the porous package component (USP <1207.2>). The test sample is placed in a closely fitting evacuation test chamber, which is equipped with an external vacuum source (USP <1207.2>). The test chamber plus test system dead space are evacuated for a predetermined period of time (USP <1207.2>). The targeted vacuum level chosen for the test is predetermined on the basis of the test sample type under evaluation (USP <1207.2>). The rise in dead space pressure (i.e., vacuum decay) is monitored for a predetermined length of time using absolute and/or differential pressure transducers (USP <1207.2>). A pressure increase that exceeds a predetermined pass/fail limit established using negative controls indicates container leakage (USP <1207.2>). Analytical service providers conduct electrical conductivity / high voltage leak detection (HVLD) testing on a range of package systems, including parenteral vials, prefilled cartridges and syringes, plastic containers and plastic bags or pouches.