Adapted from: National Network for Immunization Information) Copyright 2000, and the National Immunization Program of the Centers for Disease Control and Prevention (CDC).
The safety and effectiveness of a vaccine depends on how it is made and what it contains. There are four main ways to develop vaccines:
| Live attenuated vaccines contain bacteria or viruses that have been altered so they can’t cause disease. | Killed vaccines contain killed bacteria or inactivated viruses. | Toxoid vaccines contain toxins (or poisons) produced by the germ that have been made harmless. | Component vaccines contain parts of the whole bacteria or viruses. |
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Live Attenuated Vaccines
Live attenuated vaccines usually are created from the naturally occurring germ itself. The germs used in these vaccines still can infect people, but they rarely cause serious disease. Viruses are weakened (or attenuated) by growing them over and over again in a laboratory under nourishing conditions called cell culture. The process of growing a virus repeatedly-also known as passing–serves to lessen the disease-causing ability of the virus. Vaccines are made from viruses whose disease-causing ability has deteriorated from multiple passages.
Examples of Live Attenuated vaccines:
Measles vaccine (as found in the MMR vaccine)
Mumps vaccine (MMR vaccine)
Rubella (German measles) vaccine ( MMR vaccine)
Oral polio vaccine (OPV)
Varicella (chickenpox) vaccine
Inactivated (Killed) Vaccines
Inactivated (killed) vaccines cannot cause an infection, but they still can stimulate a protective immune response. Viruses are inactivated with chemicals such as formaldehyde.
Examples of Inactivated (Killed) vaccines:
Inactivated Polio Vaccine (IPV), which is the shot form of the polio vaccine
Inactivated Influenza Vaccine
Toxoid Vaccines
Toxoid vaccines are made by treating toxins (or poisons) produced by germs with heat or chemicals, such as formalin, to destroy their ability to cause illness. Even though toxoids do not cause disease, they stimulate the body to produce protective immunity just like the germs’ natural toxins.
Examples of Toxoid Vaccines:
Diphtheria Toxoid Vaccine (may be given alone or as one of the components in the DTP, DTaP, or dT vaccines)
Tetanus Toxoid Vaccine (may be given alone or as part of DTP, DTaP, or dT)
Component Vaccines
Some vaccines are made by using only parts of the viruses or bacteria. These vaccines cannot cause disease, but they can stimulate the body to produce an immune response that protects against infection with the whole germ. Four of the newest vaccines are made this way.
Examples of component vaccines: Haemophilus Influenzae Type B (HIb) Vaccine/Hep B Vaccine/Hep A Vaccine/ PCV (Pneumococcal Conjugate Vaccine)
