In February, The Center for Informed Consent Technology completed the following improvements to the Vaccine Ingredients Calculator:
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." 
Every vaccine comes with a lot number, like the one in this picture:
TIP: Even though it is required by Federal Law, don't assume that the doctor or nurse is going to keep accurate vaccination records for you. You should always record the lot number in your records and store them in a safe place.
As the FDA points out: "Most drugs consist of pure chemical substances and their structures are known. Most biologics, however, are complex mixtures that are not easily identified or characterized." Vaccines are chemically treated biologics; it is impossible to guarantee that different lots are the same. Lot numbers help manage the safety risks presented by this uncertainty.
Right before you or your child is vaccinated, use Vaccine Lot Search to check US Gov't data for vaccine reaction reports associated with the lot number.
You can try this right now with the lot number shown in the picture above:
If you have any questions you'd like to see addressed in future VaxCalc Progress Reports, contact us. Your message will go directly to my inbox.
Talk to you next month,
 Code of Federal Regulations, 21CFR210.3