Smallpox and vaccinia

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Info bulb.pngUse of an anti-viral to attenuate the infection, and of human Vaccinia immunoglobulin once it was available in quantity, are untried but possibly effective ways of opposing a severe Vaccinia infection, but probably would not reduce overall risk if used in anticipation.

Smallpox is not, since 1979, present in the wild in the world, and immunisation is not now conducted against it as a routine.

The Smallpox vaccine, using a similar pox virus called Vaccinia, was always as well as being the first vaccine the most intrinsically dangerous commonly used one. When Voltaire reported that 60% of people caught Smallpox, and there was a 1 in 3 mortality among them, and the previous technique if inducing immunity - variolation - had a mortality on the order of 1-2% the balance of risk was favourable.

Current estimates of death rates in widespread Smallpox immunisation are on the order of 1-2 per million, which requires a significant risk of re-introduction to make favourable except for those tasked to deal with it.

The HIV epidemic has brought renewed interest in developing attenuated poxvirus vectors as future HIV vaccines[1] and perhaps the original smallpox vaccination itself actually protected against HIV[2].

The history of smallpox and smallpox vaccination is illuminating.

  • 1802 - anti-vaccination lobby already established.
  • Acts of 1840, 1841 &1853 make vaccination successively universal, free, and finally (until 1948) compulsory.
  • 1901-2 London’s last major smallpox outbreak
  • Mid-1970s - complications of vaccinia outweigh benefits of vaccination. Vaccination abandoned apart from international travel requirements.
  • WHO strategy of surveillance and targeted vaccination
  • 1977, Somalia - last naturally occurring case. WHO declare it eradicated in 1980.