Like Gen. George Washington in 1776 during the American Revolution, President George W. Bush has gotten his smallpox vaccination as America prepares for another type of war — this one perhaps including bioterrorism.

     But Mr. Bush's effort hasn't silenced the debate over whether the vaccine should be widely distributed. Some states, most recently Alabama, have decided to move forthrightly to inoculate some 12,000 health-care workers.
     Smallpox is still one of the least understood diseases, killing many victims while leaving others with minor manifestations.
     In 1796, English physician Edward Jenner devised a vaccine against the disease, injecting individuals with vaccinia, or cowpox, a closely related virus that induced a milder reaction and immunity. Other English and European physicians and medical officials were slow to accept vaccination.
     But by the early 19th century, Dr. Jenner's discovery was in widespread use and Parliament awarded him $150,000.
     Yet 75 years before the English milestone, the American Congregational minister Cotton Mather and Boston physician Ezekial Boylston employed a similar technique in an epidemic that threatened Boston. In 1721, Mather gathered his fellow Congregational ministers and used their influential voices to persuade many Bostonians to submit to inoculation, contracting the disease voluntarily through a scratch in the skin from a knife or needle that had been embedded in the rash of a victim.
     Only in retrospect was Mather's controversial role viewed as prudent. Of the 6,000 Bostonians who contracted smallpox in 1721, 900 died. That figure likely would have been higher had 287 Bostonians not been inoculated (six of them died.)
     By 1800, Dr. Jenner's less-threatening vaccination movement had reached the Atlantic seaboard, but smallpox would be slow to leave America. Immigrants were flooding the nation's cities, overtaxing officials and resources employed in enforcement of health regulations. In addition, the rise of anti-vaccination societies kept health officials on the defensive.
     The American record improved in the final few decades of the 1800s, but smallpox cases were significant well into the 20th century, with a rate of 95.9 per 100,000 population in 1920, dwindling to 24.4 in 1931 and 11.5 in 1938. As a result of more rigorous enforcement, including the compulsory vaccination of schoolchildren, the rate was less than 0.05 per 100,000 by 1949.
     Today, Americans older than 60 may still recall their vaccination before entry into the first grade. It often erupted into an ugly, itchy scab at the site of the incision, requiring a protective dressing to prevent scratching. Second vaccinations were required for travelers to Europe, which for many induced the same scab and itch.
     Worldwide, smallpox plummeted after the World Health Organization launched its vaccination campaign in 1967. The 41 nations in which the disease was endemic saw the 10 million to 20 million cases and 2 million fatalities per year dwindle to a handful by July 1975.