smallpox vaccination

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The most effective counter measure against smallpox is vaccination before exposure. Vaccination after exposure is also effective in reducing the attack rate, and the severity of those cases that occur despite early immunisation

  • the vaccine contain live vaccinia virus
  • vaccinating with smallpox vaccine involves intradermal inoculation by multiple punctures with a specific bifurcated needle.
  • a vaccine "take" is successful when a pustule develops over six to seven days, progressive crusting then occurs in the following 8-10 days.
  • previously vaccinated individuals may have an "accelerated" response, with a pustule developing in 3-4 days and healing correspondingly quickly

Vaccination should be given to the groups of frontline workers who:

  • enter the exposed zone
  • are involved in decontamination of exposed persons or handling of exposed clothing and fomites
  • attend smallpox patients or handle contaminated clothing, bed linen and fomites, including mortuary workers involved in disposal of the deceased, and
  • laboratory workers who handle clinical specimens from cases

Currently, the only indication for vaccination in the UK is for the small number of laboratory staff who work with viruses closely related to the smallpox virus.
All individuals deemed to have been exposed to smallpox should receive post-exposure prophylaxis.

  • vaccination should be carried out as soon as possible and at most within 4 days of exposure to an infectious source, because the degree of protection diminishes as the interval between exposure and vaccination increases
  • prophylaxis should be considered in the following group of individuals:
    • individuals who were present in the exposed zone
    • frontline workers
    • contacts of cases of smallpox (1)


Last reviewed 01/2018