1 / 14

Why Smallpox Bioterrorism?

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.

lorand
Télécharger la présentation

Why Smallpox Bioterrorism?

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 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

  2. 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)

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

  4. 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

  5. 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?

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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?

  13. 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

More Related