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.