Vaccine Summary chapter 14

Vaccines & Immunity

Vaccines and Immunity

• Vaccines safely expose a person to disease antigens.
• They induce artificial active immunity, leading to high antibody titers and memory cells.
• Vaccine effectiveness varies, requiring multiple doses and periodic boosters.

Herd Immunity

• Herd immunity is the proportion of a population immune to a disease, achieved through natural or artificial means.
• High herd immunity (~95%) prevents disease spread, protecting non-immune individuals.
• Reduced vaccination rates can lower herd immunity, leading to disease resurgence.

Disease Eradication

• Vaccines have led to the eradication of diseases like smallpox and rubella.
• Polio is next in line, but faces setbacks.
• Measles elimination status is threatened by continuous transmission.

Vaccine Types/Formulations

• Live, Attenuated:
  • Microbe replicates but is avirulent.
  • Provides long-lasting immunity.
  • Dangerous for immunocompromised; rarely back-mutate.
• Inactivated: Killed
  • Microbe is dead and whole.
  • Requires boosters; safe for immunocompromised.
• Inactivated: Subunit
  • Uses only antigens; requires adjuvants; very safe.
• Conjugate
  • Antigen (polysaccharide) conjugated to another substance.
  • Boosts immune response, shorter-lived immunity, very safe.
• Inactivated: Toxoid
  • Immunizes against exotoxins.
  • Short-lived response; doesn't prevent infection.
• RNA Vaccines
  • Introduce nucleic acids coding for antigens.
  • Trigger immune response; e.g., Pfizer, Moderna COVID-19 vaccines.

RNA Vaccines (Details)

• Advantages: Does not introduce whole pathogens, mRNA breaks down quickly.
• Disadvantages: Requires cold temperatures for transport/storage.
• COVID mRNA vaccines code for the virus spike protein, triggering an immune response.

Recommended Vaccines

• CDC recommends official vaccine schedules based on safety, effectiveness, prevalence, and risk.
• States set daycare and school requirements/exemptions.

U.S. Pediatric Vaccine Schedule

• Designed to protect babies early (from ~2 months).
• Multiple vaccines at once are not harmful.

U.S. Recommended Adult Vaccines

• Annual influenza, DTaP booster (every 10 years), shingles (for adults over 50), pneumococcal pneumonia (adults over 65).

Vaccines for Special Populations

• Rabies (vets, wildlife biologists), Anthrax, smallpox (military), Hepatitis B (healthcare workers), Hepatitis A, typhoid (travelers).