Smallpox was eradicated by 1979 and vaccination against the disease gradually ended around the world. But stockpiles of the smallpox virus remain in laboratories in the US, Russia and possibly other nations. Recent fears of bioterrorism have ignited concerns that these stockpiles could be used to introduce the potentially deadly disease into the population, which is at present ill-prepared to deal with a potential outbreak. If introduced into America or Europe, smallpox would spread rapidly at first, infecting 6 to 12 people for each individual already infected.
As steps were taken to hinder the spread of the disease--including mass vaccination campaigns, restriction of infected individuals' movement and quarantines--the rate of disease spread would fall. Nonetheless, significant epidemics could result, particularly if there were delays in detecting the first cases or in setting up effective public health interventions.
In the US, Health and Human Services Secretary Tommy Thompson announced plans to buy as many as 300 million doses of smallpox vaccine. But several health experts have warned against a national vaccination program, citing potentially serious side effects including as many as 300 deaths.
Other experts argue that once an outbreak has occurred, restricting mass transportation and informing the public about the nature of the outbreak and how to minimize the risk of illness may more effectively prevent the spread of disease than isolating everyone who has been exposed. The smallpox vaccine can also be used to treat the infection if given in the days immediately after exposure.