Overview
This lecture explains the main components of vaccines, how they are designed, and the specific roles of various vaccine ingredients in creating effective and safe immunization.
Vaccine Components and Their Purposes
- Vaccines contain carefully chosen ingredients, each tested for safety and efficacy.
- The main active component is the antigen or its genetic blueprint, which triggers an immune response.
- Antigens can be proteins, sugars, or whole organisms in weakened or inactive forms.
- Some vaccines use genetic material to instruct the body to make antigens.
Main Vaccine Design Approaches
- Whole-microbe approaches use either inactivated (killed) or live-attenuated (weakened) viruses/bacteria.
- Inactivated vaccines require safe labs and often multiple doses (e.g., flu, polio).
- Live-attenuated vaccines use weak, live microbes and may not suit people with weak immune systems (e.g., MMR, chickenpox).
- Viral vector vaccines use a harmless virus to deliver a protein from the target germ to trigger immunity (e.g., Ebola vaccine).
- Subunit vaccines use only specific parts (proteins/sugars) of the germ and avoid using the whole microbe.
- Most childhood vaccines are subunit vaccines (e.g., for whooping cough, tetanus).
- Genetic (nucleic acid) vaccines use sections of DNA or RNA to code for proteins, not the entire microbe.
Other Common Vaccine Ingredients
- Preservatives prevent contamination of multi-dose vials; 2-phenoxyethanol is common and safe.
- Stabilizers (e.g., sugars, gelatin, amino acids, proteins) prevent chemical reactions and keep components stable.
- Surfactants keep the mixture uniform and prevent clumping.
- Residuals are tiny, inactive traces from the manufacturing process (e.g., egg proteins, yeast, antibiotics).
- Diluent, usually sterile water, dilutes vaccine to the right concentration.
- Adjuvants, often aluminum salts, enhance the immune response and are safe for human use.
Key Terms & Definitions
- Antigen — A substance that triggers an immune response, often a protein or sugar from a pathogen.
- Live-attenuated vaccine — Vaccine using a weakened, live germ to stimulate immunity.
- Inactivated vaccine — Vaccine using a killed germ, incapable of causing disease.
- Viral vector vaccine — Vaccine that uses a harmless virus to deliver disease-specific proteins.
- Subunit vaccine — Vaccine containing only specific pieces of the germ needed for immunity.
- Nucleic acid vaccine — Vaccine containing DNA or RNA instructions so the body makes its own antigens.
- Adjuvant — Ingredient that boosts the body’s immune response to the vaccine.
Action Items / Next Steps
- Review types of vaccines and their components for understanding immunization strategies.
- Read related Q&A sections on vaccine safety and immunization principles if further detail is needed.