Smallpox Vaccine and Use Sources: Bill Atkinson, Mike Lane, Walt Orenstein, and Joanne Cono, CDC

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Smallpox Vaccine and Use Sources: Bill Atkinson, Mike Lane, Walt Orenstein, and Joanne Cono, CDC Joel Ackelsberg, MD, MPH New York City Department of Public Health Communicable Disease Program jackelsb@health.nyc.gov Variolation “Artificial” infection of susceptible person with variola virus
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Smallpox Vaccine and UseSources: Bill Atkinson, Mike Lane, Walt Orenstein, and Joanne Cono, CDCJoel Ackelsberg, MD, MPHNew York City Department of Public HealthCommunicable Disease Programjackelsb@health.nyc.govVariolation
  • “Artificial” infection of susceptible person with variola virus
  • Practiced in China and probably India in the 9th century
  • Infection by different routes
  • Variolation
  • Cutaneous inoculation resulted in severe local lesions, usually with many satellite pustules
  • Usually caused a generalized rash and severe constitutional symptoms
  • Could be fatal, and could be transmitted to contacts
  • Smallpox – Boston, 1752Variolation2,12430 (1.4)Smallpox*5,545537 (9.7)CasesDeaths*28% of smallpox cases caused by variolationProtection from Smallpox
  • Folklore in Europe that milkmaids rarely pockmarked
  • Belief that protection from smallpox resulted from infection acquired from cows
  • Jenner observed that some with history of cowpox “resisted” variolation
  • Jenner’s Experiment
  • Transferred “matter” from the hand of an infected dairymaid to 8 year-old James Phipps on 14 May 1796
  • Variolation unsuccessful on 1 July 1796
  • Phipps did not respond to variolation 5 years after original vaccination
  • Vaccination
  • Jenner’s observations soon reproduced by others
  • Practice quickly spread throughout Europe
  • Benjamin Waterhouse performed first vaccinations in U.S. in Boston, 1800
  • Smallpox Vaccine
  • Until the mid-19th century vaccine was generally transferred from arm-to-arm
  • Also distributed dried using threads, ivory points, or glass slides
  • Cows first used in Italy in early 19th century
  • “…it now becomes too manifest to admit of controversy, that the annihilation of the Small Pox, the most dreadful scourge of the human species, must be the final result of this practice.”-Edward Jenner, 1801Smallpox Vaccine
  • Original material used by Jenner was probably cowpox
  • Vaccine constituent changed from cowpox to vaccinia during the 19th century
  • Vaccinia Virus
  • Origin of vaccinia virus unknown
  • Genetically distinct from cowpox and variola
  • May be a virus now extinct in nature
  • Vaccinia Virus
  • Multiple strains with different levels of virulence for humans and animals
  • U.S. vaccine (Dryvax, Wyeth Laboratories) contains New York City Board of Health strain
  • Vaccine Production
  • Virus grown on skin of calves, sheep, and water buffalo
  • Material from lesions harvested before crusting to maximize viral titer
  • Pulp ground and originally mixed with 40%-60% glycerol and distributed in glass capillary tubes
  • Smallpox (Vaccinia) Vaccine
  • 15 million doses now in stock
  • 100-dose vials
  • Contract for additional 54 million doses produced on cell culture media
  • Response to Vaccination
  • Neutralizing antibody:
  • 10 days after primary vaccination
  • 7 days after revaccination
  • Considered fully protected after a successful response demonstrated at vaccination site
  • Vaccine Efficacy
  • Clinical efficacy estimated in household contact studies
  • 91%-97% reduction in cases among contacts with vaccination scar
  • Studies did not consider time since vaccination or potency of vaccine
  • Post Exposure Vaccine Efficacy
  • Clinical efficacy estimated in household contact studies
  • SAR 2%-75%, varied by time since exposure
  • Disease generally less severe (modified type) in those with post exposure vaccination
  • Post Exposure Vaccine Efficacy% with smallpox29.547.675.096.31.921.8Postexp vaccNever vaccVacc <10 daysNever vaccVacc <7 daysNever vaccMadrasPakistanPakistanDuration of Immunity
  • High level of protection (~100%) for 3 years following vaccination
  • Substantial but waning immunity for >10 years
  • Reduction in disease severity
  • CFR by Vaccination Status, Europe, 1950-1971 Mack TM. J Infect Dis 1972;125:161-9.Duration of Protection††From Outbreak in Liverpool, England, 1902-1903In Fenner F et al. Smallpox and its Eradication, pp53Antibody Persistence
  • Level of antibody that protects against smallpox infection unknown
  • Neutralizing antibody >1:10 persists up to 30 years following 3 doses
  • Antibody Persistence Following Second RevaccinationBaruch El-Ad, et al J Infect Dis 1990;161:446-8. Vaccine Administration
  • Surgical needle
  • Vaccinostyle
  • Rotary lancet
  • Jet injector
  • Bifurcated needle*
  • *Only administration technique currently in use.Clinical Response to Vaccination*Symptom/signPapuleVesiclePustuleMaximum erythemaScabScab separationTime after Vacc3 days5-6 days7-11 days8-12 days14 days21 days*Typical response in a nonimmune personEvolution of Smallpox Vaccine Recommendations
  • 1971 Discontinue routine vaccination
  • 1976 Discontinue vaccination of HCWs
  • 1980 Vaccine recommended for lab
  • workers
  • 1991 “Vaccinia vaccine”
  • 1991 Consider vaccine for HCWs
  • exposed to recombinant vaccinia
  • 2001 Bioterrorism guidelines
  • Smallpox (Vaccinia) VaccineIndications in Nonemergency Situations
  • Laboratory workers who handle cultures or animals infected with nonhighly attenuated vaccinia
  • Consider for other health care workers with contact with contaminated material
  • (first response teams)
  • Smallpox (Vaccinia) VaccineIndications in Emergency Situations
  • Persons exposed to initial release
  • Close contact with confirmed or suspected case
  • Direct care or transportation of confirmed or suspected case
  • Laboratory personnel
  • Persons with risk of contact with infectious materials from case
  • Transmission of Vaccinia
  • Vaccinia virus may be recovered from the site of vaccination from development of papule (2-5 days) until scab separates from the skin
  • Household contacts at highest risk of contact transmission
  • Major Complications of Smallpox Vaccination
  • Inadvertent autoinoculation
  • Eczema vaccinatum
  • Generalized vaccinia
  • Progressive vaccinia (vaccinia necrosum)
  • Postvaccinal encephalitis
  • Other dermatologic conditions
  • Contraindications and PrecautionsNonemergency Situations
  • Severe allergic reaction to prior dose or vaccine component
  • Eczema, history of eczema, or household contact with eczema or history of exzema
  • Other skin conditions
  • Immunosuppression or immuno-suppressed household contact
  • Pregnancy
  • Age <18 years
  • Contraindications and PrecautionsEmergency (post-release) Situations
  • Exposed persons – no contraindications
  • Unexposed persons – same as nonemergency situations
  • Vaccinia Immune Globulin
  • Immunoglobulin fraction of plasma from persons vaccinated with vaccinia vaccine
  • Effective for treatment of eczema vaccinatum, progressive vaccinia, severe generalized vaccinia, and ocular vaccinia
  • Not effective in postvaccinial encephalitis
  • Contraindicated in vaccinial keratitis
  • Adverse Reaction Rates**Adapted from CDC.. MMWR 2001;50(RR-10)Risk Factors
  • Eczema (contact too)
  • Age less than 1 yr
  • Anaphylaxis
  • Neomycin, Streptomycin, Tetracycline
  • Immunosuppression
  • Cancer (disease or therapy)
  • HIV
  • Iatrogenic (transplant)
  • Bilateral Ocular autoinocuation in primary vaccinee43Eczema Vaccinatum44Eczema Vaccinatum (contact)45Progressive Vaccinia46Progressive Vaccinia47Public Health Factors in Choosing a Vaccination Strategy
  • Vaccine Supply
  • Extent of Outbreak
  • Risk and acceptability of vaccine-related adverse events
  • 48Key Containment Strategies49Eradication Strategy of the 1970s
  • Vaccination of close contacts of cases
  • Occasionally supplemented with broader campaigns
  • Vaccine was readily available
  • 50Smallpox Realities in 2001
  • No cases of smallpox
  • Threat unknown
  • Susceptible population
  • Many people at risk for adverse events from vaccination
  • Limited vaccine supplies
  • 51Future Vaccine Supplies
  • Contracts underway
  • Acambis/Baxter International
  • Increasing amounts available throughout next year (IND)
  • Next step - clinical trials
  • Expect ~300 million doses by late 2002
  • 52Ring Vaccination StrategyContact to ContactContact to CaseCase53Ring Vaccination Strategy
  • Primary strategy to stop transmission
  • Depends upon prompt identification of contacts
  • Judicious use of vaccine supply
  • Minimizes risks of adverse events
  • 54Contact Vaccination
  • Face-to-face contact (<= 6.5 feet) and household members at greatest risk
  • May prevent or lessen severity of disease (4-day window)
  • Followed by monitoring for fever
  • 55Contraindications for Vaccination of ContactsNONEIn general, the risk of developing smallpox for face-to face contacts outweighs the risk of developing vaccine complications for those contacts with contraindications to vaccination.56Vaccination of Contacts of Contacts
  • Household members of a contact without contraindications
  • Household members of a contact with contraindications, who are not vaccinated, must avoid the contact (18 days)
  • 57Contraindications for Vaccination of Non-Contacts
  • Immunodeficiency *
  • Allergies to polymyxin B, streptomycin, tetracycline, or neomycin
  • Eczema; including past history *
  • Pregnancy
  • Acute or chronic skin conditions (until resolved)
  • * Risk of accidental inoculation from household vaccinee’s site58Vaccination Clinics
  • Why?
  • Minimizes vaccine wastage
  • Security issues
  • 59Vaccine Mobilization
  • Released by Director of CDC
  • Priority given to:
  • Areas with confirmed cases
  • Areas with probable cases
  • 60Vaccine Deployment
  • Amount determined by:
  • Number of cases
  • Number of contacts
  • Number of areas affected
  • Number of personnel to be vaccinated
  • Vaccination strategy
  • 61Dilution of Vaccine
  • May provide valuable alternative for personnel with time to verify vaccine take
  • Decisions will be made at the Federal level (use, dilution, vaccination group)
  • 62Supplemental CDC Strategies
  • Broader vaccination campaign possible, if:
  • Number of cases or locations too large for effective contact tracing
  • No decline in number of new cases after 2 generations
  • No decline after 30% of vaccine has been used
  • 63Limitations of CDC Vaccine Strategy in Large Cities
  • Will hospital staff, ambulance drivers, public health employees, and police work without protection?
  • After vaccination, these employees will not be able to work for ~ 2 weeks
  • How will ring vaccination work if exposure occurs in a subway?
  • Will the public go along with this strategy?
  • 64What Hospitals Can Do Now
  • Develop effective infection control procedures (pre- and post-outbreak)
  • Pre-identify volunteer staff who may have some immunity to smallpox
  • Prior vaccinees
  • Veterans (pre-1990)
  • Begin to consider effective internal vaccination strategies
  • 65
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