Why Smallpox Bioterrorism?

      Stable aerosol Virus Easy to Produce Infectious at low doses Human to human transmission 10 to 12 day incubation period High mortality rate (30%)  CDC Materials

•Small Pox Vaccine History

     1000 AD - China, deliberate inoculation of smallpox into skin or nares resulting in less severe smallpox infection. Vaccinees could still transmit smallpox 1796 - Edward Jenner demonstrated that skin inoculation of cowpox virus provided protection against smallpox infection 1805 - Italy, first use of smallpox vaccine manufactured on calf flank 1864 - Widespread recognition of utility of calf flank smallpox vaccine 1940’s - Development of commercial process for freeze-dried vaccine production (Collier)

Herd Immunity

  Smallpox Spreads to the Non-immune   Immunization Slows the Spread Dramatically Epidemics Die Out Naturally Herd Immunity Protects the Unimmunized

Smallpox Vaccine

   Live Virus Vaccine (Vaccinia Virus)   Not Cowpox, Might be Extinct Horsepox Must be Infected to be Immune Crude Preparation We Have Now   Prepared from the skin of infected calves Filtered, Cleaned (some), and Freeze-dried New Vaccine is Clean, but still Live

Complications of Vaccination

    Local Lesion  Can be Spread on the Body and to Others Progressive (Disseminated) Vaccina  Deadly Like Smallpox, but Less Contagious Encephalitis Heart Disease?

Historic Probability of Injury

    Small Risk from Bacterial and Viral Contaminants Small Risk of Allergic Reaction 35 Years Ago  5.6M New and 8.6M Revaccinations a Year  9 deaths, 12 encephalitis/30-40% permanent Death or Severe Permanent Injury 1/1,000,000  Mostly among immunsupressed persons

Global Eradication Program

    1950 - Pan American Sanitary Organization initiated hemisphere-wide eradication program 1967 - Following USSR proposal (1958) WHO initiated Global Eradication Program   Based on Ring Immunization Vaccinate All Contacts and their Contacts   Isolate Contacts for Incubation Period Involuntary - Ignore Revisionist History 1977 - Oct. 26, 1977 last known naturally occurring smallpox case recorded in Somalia 1980 - WHO announced world-wide eradication

Eradication Ended Vaccinations

   Cost Benefit Analysis    Vaccine was Very Cheap Program Administration was Expensive Risks of Vaccine Were Seen as Outweighing Benefits Stopped in the 1970s Immunity Declines with Time

Universal Vulnerability

   Agriculture and Smallpox  Stays Endemic or Dies Out Forever  Most Communities had Significant Immunity Isolated Communities   Synchronous Infection Break Down of Social Order Now the Whole World is Susceptible

How Have Risks Changed?

   Immunosuppressed Persons Cannot Fight the Virus and Develop Progressive Vaccinia Immunosuppression Was Rare in 1970 Immunosuppression is More Common  HIV, Cancer Chemotherapy, Arthritis Drugs, Organ Transplants

Role of Medical Care

  Smallpox  Can Reduce Mortality with Medical Care    Huge Risk of Spreading Infection to Others Very Sick Patients - Lots of Resources Cannot Treat Mass Casualties Vaccinia   VIG - more will have to be made Less sick patients - longer time

Complications Last time - 1947 New York Outbreak

     Case from Mexico 6,300,000 Vaccinated in a Month 3 Deaths from the Smallpox 6 Deaths from the Vaccine Would Have Been Much Higher Without Vaccination?

What would happen now?

   Assume 1,000,000 Vaccinated in Mass Campaign with No Screening Assume 1.0% Immunosuppressed   10,000 Immunosuppressed Persons Probably Low, Could be 2%+ Potentially 1-2,000+ Deaths and More With Severe Illness