Overview
This lecture explains how vaccines work, their benefits and drawbacks, and why they are important for individual and public health.
How Vaccines Work
- After exposure to a pathogen, the immune system develops immunity, preventing future illness from that pathogen.
- Vaccines contain weakened or inactivated pathogens which cannot cause disease but still trigger an immune response.
- The body produces antibodies and develops immunity without the risk of becoming ill.
Benefits of Vaccines
- Vaccines protect individuals from catching serious diseases.
- Widespread vaccination controls or eliminates diseases like polio, smallpox, measles, and whooping cough.
- Vaccines prevent epidemics (large outbreaks) by limiting disease spread across populations.
- Herd immunity occurs when enough people are immune, making it hard for pathogens to spread—even protecting unvaccinated individuals.
Drawbacks and Limitations
- Vaccines do not always grant full immunity, but effectiveness is usually checked after major vaccinations.
- Some people may have adverse reactions, such as swelling, fever, or very rarely, seizures.
- Severe reactions are extremely rare.
Key Terms & Definitions
- Pathogen — a microorganism that can cause disease (e.g., bacteria, viruses).
- Antigen — a substance on pathogens that triggers an immune response.
- Antibody — a protein produced by the immune system to neutralize pathogens.
- Immunity — protection against a specific disease, preventing future infection.
- Herd Immunity — when enough people in a population are immune so the disease cannot easily spread.
- Epidemic — a large outbreak of disease in a community or region.
Action Items / Next Steps
- Review the diseases covered by standard vaccines.
- Understand the concept and importance of herd immunity.
- Study side effects and limitations of vaccines.