VaxCalc Vaccine Lot Search data currently covers vaccine reactions reported from January 01, 2010 through March 14, 2018.
The FDA defines a vaccine lot number as a code "from which the complete history of the manufacture, processing, packing, holding, and distribution of a batch or lot of drug product or other material can be determined."
The data is taken directly from VAERS data sets. Established in 1990, the Vaccine Adverse Event Reporting System (VAERS) is a national early warning system to detect possible safety problems in U.S.-licensed vaccines. VAERS is co-managed by the Centers for Disease Control and Prevention (CDC) and the U.S. Food and Drug Administration (FDA).