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Vaccine Types and Characteristics

Types of Vaccines

  • Two main types of vaccines:
    • Cellular (whole) vaccine
    • Acellular vaccine

Whole Vaccine

  • Two types of whole vaccines:
    • Live attenuated vaccine
    • Killed/inactivated vaccine

Live Attenuated Vaccine

  • Live, but weakened pathogen.
  • Pros:
    • Robust immune response.
    • Resembles actual pathogen.
    • Response is typically achieved through mutation after multiple passages of the pathogen.
  • Cons:
    • Time-consuming to make desired proteins.
    • Small chance to revert back from mutation.
  • Examples: MMR (measles, mumps, rubella), smallpox vaccine (Edward Jenner).

Killed/Inactivated Vaccine

  • Made by chemical treatment (formaldehyde), heat, or radiation treatment of the pathogen.
  • Pros:
    • Cannot revert back.
    • Can be stored and transported in freeze-dried form.
  • Cons:
    • Weaker immune response due to denatured protein.
  • Examples: Polio vaccine, flu vaccine.

Acellular Vaccine

Subunit Vaccine

  • Administration of just the antigen rather than the entire pathogen.
  • Pros:
    • Robust immune response.
  • Cons:
    • Takes time to identify the ideal combo and manufacturing process.
  • Example: HPV vaccine.

Toxoid Vaccine

  • Vaccine for bacterial toxins.
  • When the toxin is more dangerous than the bacteria itself, the vaccine neutralizes the toxin, and the body handles the bacteria.
  • Made by production and purification of toxin.
  • The toxin is inactivated using formaldehyde.
  • After purification, there is always a trace amount of formaldehyde.
  • Examples:
    • DTaP (for young children): Diphtheria, Tetanus, Pertussis
    • Tdap (for teens & adults)

Polysaccharide Vaccine

  • Made up of sugar.
  • Does not last long; cannot stimulate enough of an immune response.
  • Used against capsulated bacteria, i.e., meningococcal vaccine.

Conjugated Vaccine

  • Newer version of polysaccharide vaccine.
  • Carbohydrate is linked to an antigen (i.e., diphtheria toxin).
  • Development takes time.

Nucleic Acid Vaccine

  • Uses genetic material to trigger immune response.
  • Pros:
    • Fast to manufacture.
    • Native antigen (similar to antigen) → robust immune response.

Adjuvants

  • Stimulate PRR (pathogen recognition receptor), which gives a more robust adaptive immune response.