The hepatitis B vaccine (HepB) used currently in the United States is synthetically made from recombinant DNA. Let me break that statement down and tell you exactly what it means. This vaccine is considered synthetic because it is entirely made in a lab and contains no human blood products. Why would it ever contain human blood, you ask. Well, the virus is found in human blood, so you may suspect that human blood would be used to make the vaccine. In this case, no human products are ever used in the making of the vaccine, and let me tell you why: because of the use of recombinant DNA techniques.