In most countries, government authorities regulate the production of biologics. In general, regulatory authorities license establishments that produce vaccines and inspect those premises to ensure that the facilities and the methods used are satisfactory. All vaccines are checked for safety, purity, potency, and efficacy. Safety tests include confirmation of the identity of the organism used, freedom from contamination with extraneous organisms, and host and non-host safety tests. Because the living organisms found in vaccines normally die over time, it is necessary to ensure that they will be effective even after storage (stability). Although properly stored vaccines may still be efficacious after the expiration of their designated shelf life, this must never be assumed; expired vaccines should not be used.