Vaccination History โ Study Notes
1. Introduction
Vaccination is the administration of antigenic material to stimulate an individualโs immune system to develop adaptive immunity to a pathogen. It has revolutionized public health by drastically reducing morbidity and mortality from infectious diseases.
2. Timeline of Vaccination
| Year | Milestone |
|---|---|
| 1796 | Edward Jenner develops smallpox vaccine using cowpox virus. |
| 1885 | Louis Pasteur creates rabies vaccine. |
| 1923 | Diphtheria toxoid vaccine introduced. |
| 1955 | Jonas Salk develops inactivated polio vaccine. |
| 1963 | Measles vaccine licensed. |
| 1971 | MMR (Measles, Mumps, Rubella) combined vaccine introduced. |
| 2006 | HPV vaccine approved. |
| 2020 | First mRNA vaccines (COVID-19) authorized. |
3. How Vaccines Work
Vaccines introduce a harmless component of a pathogen (antigen) to the body, prompting the immune system to produce antibodies. Upon subsequent exposure, the immune system recognizes and neutralizes the pathogen rapidly.
Diagram: Immune Response to Vaccination
4. Types of Vaccines
- Live Attenuated: Weakened form of the pathogen (e.g., MMR, Varicella).
- Inactivated: Killed pathogen (e.g., Polio, Hepatitis A).
- Subunit, Recombinant, Conjugate: Specific pieces of the pathogen (e.g., HPV, Hib).
- Toxoid: Inactivated toxins (e.g., Diphtheria, Tetanus).
- mRNA: Encodes antigenic proteins (e.g., Pfizer-BioNTech, Moderna COVID-19).
- Viral Vector: Uses a harmless virus to deliver genetic material (e.g., AstraZeneca COVID-19).
5. Impact on Public Health
- Eradication of smallpox (1980).
- Near eradication of polio.
- Significant reduction in measles, diphtheria, pertussis, and tetanus cases.
- Herd immunity protects unvaccinated individuals.
6. Emerging Technologies
- mRNA Vaccines: Rapid development and adaptability; used in COVID-19.
- DNA Vaccines: Under research; potential for long-lasting immunity.
- Nanoparticle Vaccines: Enhanced delivery and stability.
- Universal Influenza Vaccines: Target conserved viral regions for broad protection.
- Self-Amplifying RNA Vaccines: Lower dose requirements, faster response.
Diagram: mRNA Vaccine Mechanism
7. Surprising Facts
- Smallpox is the only human disease eradicated by vaccination.
- The human brain has more connections than there are stars in the Milky Way.
- The 2020 COVID-19 mRNA vaccines were developed and authorized in less than a yearโan unprecedented speed in vaccine history.
8. Ethical Issues
- Informed Consent: Ensuring individuals understand benefits and risks.
- Access and Equity: Distribution disparities between high- and low-income countries.
- Mandates vs. Autonomy: Balancing public health and individual rights.
- Research Ethics: Safety in clinical trials, especially in vulnerable populations.
- Data Privacy: Handling personal health information during vaccination campaigns.
9. Recent Research
A 2021 study published in Nature Reviews Immunology highlighted the rapid development and deployment of mRNA vaccines against COVID-19, noting their high efficacy and potential for future applications (Krammer, F., 2021. โSARS-CoV-2 vaccines in development,โ Nature Reviews Immunology, 21: 273โ284).
10. Quiz Section
1. Who developed the first vaccine and for which disease?
2. Name two types of vaccines and give an example for each.
3. What is herd immunity and why is it important?
4. What ethical issue arises with vaccine mandates?
5. Which technology enabled rapid COVID-19 vaccine development in 2020?
11. Key Takeaways
- Vaccination is a cornerstone of modern medicine.
- New technologies (mRNA, DNA, nanoparticles) are shaping future vaccine development.
- Ethical considerations are critical in vaccine research, distribution, and policy.
- Ongoing research continues to improve vaccine efficacy, safety, and accessibility.
12. References
- Krammer, F. (2021). SARS-CoV-2 vaccines in development. Nature Reviews Immunology, 21, 273โ284.
- World Health Organization. Vaccine History Timeline.
- CDC. Vaccine Types and Mechanisms.
End of Revision Sheet