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Types of Vaccines

Types of Vaccines

Scientists take many approaches to designing vaccines. These approaches are based on information about the germs (viruses or bacteria) the vaccine will prevent, such as how it infects cells and how the immune system responds to it. Scientist also consider the different parts of the world the vaccine may be used, such as environmental conditions (e.g., temperature, risk of exposure) and the delivery options available geographically.81 Today there are five main types of vaccines. 

 

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    Click on each type to learn more.

 

      • These vaccines contain a version of the living virus that has been weakened so that it does not cause serious disease in people with healthy immune systems.81
      • Live, attenuated vaccines are the closest thing to a natural infection, they are good teachers for the immune system.81
        • Examples include:
          • measles, mumps, and rubella vaccine (MMR)
          • varicella (chickenpox) vaccine.
      • Even though these vaccines are very effective, not everyone can receive them. Children with weakened immune systems—for example, those who are undergoing chemotherapy—cannot get live vaccines.81
      • These vaccines are made by inactivating, or killing, the virus during the process of making the vaccine.81
        • Examples include:
          • Inactivated polio vaccine
      • Inactivated vaccines produce immune responses in different ways than live, attenuated vaccines.81
      • Often, multiple doses are necessary to build up and/or maintain immunity.81
      • Prevent diseases caused by bacteria that produce toxins (poisons) in the body.81
      • In the process of making these vaccines, the toxins are weakened so they cannot cause illness. Weakened toxins are called toxoids.81
      • When the immune system receives a vaccine containing a toxoid, it learns how to fight off the natural toxin.81
        • Examples include:
          • DTaP vaccine- contains diphtheria and tetanus toxoids
      • Include only parts of the virus or bacteria, or subunits, instead of the entire germ.81
      • Because these vaccines contain only the essential antigens and not all the other molecules that make up the germ, side effects are less common.81
        • Examples include:
          • The pertussis (whooping cough) component of the DTaP vaccine
      • Fight bacteria that have antigens with an outer coating of sugar-like substances called polysaccharides. This type of coating disguises the antigen, making it hard for immature immune system to recognize it and respond to it.81
      • Conjugate vaccines are effective for these types of bacteria because they connect (or conjugate) the polysaccharides to antigens that the immune system responds to very well.81
      • This linkage helps the immature immune system react to the coating and develop an immune response.81
        • Examples include:
          • Haemophilus influenzae type B (Hib) vaccine.