What ingredients are in vaccines?

Antigens

All vaccines contain antigens. Antigens make vaccines work. They prompt the body to create the immune response needed to protect against infection. Antigens come in several forms. The form used in a vaccine is chosen because studies show it is the best way to protect against a particular infection. Antigen forms include:

• Inactivated (or killed) viruses. These viruses cannot cause even a mild illness. However, the body still recognizes the virus and creates an immune response to protect itself. The polio, hepatitis A, rabies and some influenza vaccines contain inactivated viruses.
• Weakened live viruses. These are too weak to cause disease but can still prompt an immune response. Live vaccines tend to cue a stronger immune response. Measles, mumps, and rubella (MMR), rotavirus, chickenpox (varicella), and one type of influenza (flu) vaccine contain weakened live viruses.
• Virus subunit. These are made up of a fragment or portion of the dead virus. This will prompt the body’s protective immune response. Some vaccines made this way include the hepatitis B and human papillomavirus (HPV) vaccines.
• Partial bacteria. Vaccines that contain partial bacteria have a fragment or portion of the dead bacteria to prompt a protective immune response. Some vaccines are made with partially purified bacteria, including the Haemophilus influenzae type b (Hib), pneumococcal, meningococcal, and DTaP (diphtheria, tetanus, and pertussis) vaccines.

source: HealtyFamilies.org