Lecture Notes: Using Vaccines to Eradicate Diseases

Smallpox Eradication

• First and only human disease eradicated
  • Smallpox targeted early for vaccination due to its severity.
  • Initially addressed through variolation.
• Impact of Smallpox
  • In the 18th century, killed 1 out of every 10 children.
  • Killed 300-500 million people in the 20th century.
  • No effective treatment developed; vaccination was the sole prevention.
• Vaccination Efforts
  • Infects only humans; no animal reservoirs.
  • WHO's worldwide vaccination program began in 1967.
  • Ring vaccination: easier due to symptomatic nature of disease.
  • Last natural case in Somalia in 1977; declared eradicated in 1980.
• Personal Impact
  • Earlier generations vaccinated; current generations not, due to eradication.

Other Diseases Targeted by WHO

• Guinea Worm
  • Initially transmitted by humans, now by animals.
• Polio
  • Eradication efforts began in 1988.
  • Human-to-human transmission.

Challenges in Polio Eradication

• Progress and Setbacks
  • Cases reduced from 300,000/year to 483 by 2001.
  • Geopolitical issues affected efforts, e.g., Nigeria (2003) and Pakistan (2009).
  • Violence against vaccination workers.
• Transmission and Vaccination Issues
  • Polio often carried asymptomatically, complicating eradication.
  • Spread through sewage (fecal-oral transmission).
  • Vaccine-derived virus: mutation risks from oral polio vaccine.
• Current Situation
  • Two of three strains eradicated by fall 2019.
  • Focus on remaining strain and vaccine-derived virus challenges.

Conclusion

• Eradicating diseases is challenging due to biological and geopolitical factors.
• Videos and additional resources to be provided for further understanding.
• Upcoming topics include different types of vaccines.