VaxCalc Vaccine Lot Search data currently covers vaccine reactions reported from January 01, 2010 through July 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).
You may wish to view, read, and print out the Vaccine Injury Table, which is part of US Federal law, and states: "the following is a table of vaccines, the injuries, disabilities, illnesses, conditions, and deaths resulting from the administration of such vaccines, and the time period in which the first symptom or manifestation of onset or of the significant aggravation of such injuries, disabilities, illnesses, conditions, and deaths is to occur after vaccine administration for purposes of receiving compensation under the Program." The Vaccine Injury Table can be a useful reference when speaking with your doctor.