The US, United Kingdom and Canada are buying enough smallpox vaccine to inoculate every citizen, although mass vaccination is not yet planned in Canada.
To combat possible bioterrorism, the US is stockpiling 350 million doses, while the UK is spending £32 million for an undisclosed amount of vaccine to add to existing stocks. Canada recently announced that it is buying 10 million concentrated doses — enough to vaccinate 30 million people — for $40 million.
All 3 countries plan to vaccinate key health workers. Health Canada is going to inoculate 500 professionals considered at highest risk of contracting the disease, while the US intends to vaccinate 500 000 health care and emergency workers. Details of the UK's plan are still being developed.
All 3 countries are avoiding mass vaccination for the time being due to potential risks, estimated at a 1-in-1-million chance of death and a 1-in-300 000 chance of serious side effects.
If there is an outbreak, Health Canada and the UK will employ “ring immunization,” which involves only people who may have had contact with known victims. This was the strategy that in 1979 finally succeeded in eradicating naturally occurring smallpox. The US intends to immunize everyone within 5 days of an outbreak.
Laboratories in the US and Russia are the only known repositories of the virus, but the US says Iraq and North Korea have covert stocks. The Russian scientist in charge of one of the last known caches of the virus said mass vaccination should be reintroduced because terrorists could easily entice underpaid researchers in the former Soviet Union into turning smallpox into a tool for bioterrorists.
“Smallpox is a very dangerous weapon in the hands of terrorists and you don't need some clever way of delivering it,” said Dr. Lev Sandakhchiev, director of Russia's Scientific Centre of Virology and Biotechnology. “All you need is a sick fanatic.” — Cathel Kerr, Fife, Scotland; Barbara Sibbald, CMAJ