What is the smallpox vaccine?

Definition

The development of a smallpox vaccine began with variolation, which was the practice
of removing material from the scabbing pustules of infected people and
administering that material to healthy people to induce a milder form of smallpox
and subsequent immunity. Smallpox, caused by the Variola
major virus, is thought to have arisen as many as ten thousand years
ago in northern Africa and spread to the rest of the world by the seventeenth
century, leaving millions dead in its wake.

Although used in Asia and the Middle East as early as the eleventh century, variolation was not in widespread use in Europe until the late eighteenth century. Although variolation was often fatal, the total number of smallpox cases was significantly reduced because of the technique.

Vaccine Development

In 1774, an English farmer made the observation that milkmaids who became
infected with cowpox, a mild disease caused by the vaccinia virus, seldom
became infected with smallpox. The farmer immunized his family against smallpox by
infecting them with cowpox taken from a cow’s udder.

Edward
Jenner, an English physician, is credited with developing the
smallpox vaccine. In 1796, Jenner removed fluid from a cowpox pustule of a
milkmaid and inoculated an eight-year-old boy. The boy was exposed to material
taken from a fresh smallpox lesion six weeks later but did not develop smallpox.
By the early to mid-nineteenth century, inoculation with cowpox replaced
variolation. Jenner referred to his preparation as a vaccine
because the material came from a cow (vacca, in Latin).

The modern vaccine uses an attenuated vaccinia strain. After administration, a pustule develops, eventually scabs over, and falls off. For a few days after vaccination, the patient may have mild symptoms. Rarely do serious side effects develop. Vaccination within three to seven days of exposure to the smallpox virus can result in a significant reduction in the severity of the symptoms.

In 1982, after smallpox had been eradicated and the United States terminated
its mandatory vaccination program, production of the smallpox vaccine ceased. In
2007, the U.S. Food and Drug Administration authorized the production of a
newer and safer vaccine to be placed in the Strategic National Stockpile to be
used in the event of national emergency by the Centers for Disease Control and
Prevention.

Impact

The development of the smallpox vaccine led to the eventual eradication of the
disease. Although smallpox had been virtually eradicated from developed countries
by the 1950’s, epidemics continued in developing countries. In 1967, the
World Health
Organization (WHO) began a worldwide eradication campaign
that led to the last endemic case of smallpox, which was reported in 1977. In
1980, WHO announced that the world was free of smallpox.

Bibliography

Baciu, Alina, et al., eds. The Smallpox Vaccination Program: Public Health in an Age of Terrorism. Washington, D.C.: National Academies Press, 2005.

Henderson, D. A., and Richard Preston. Smallpox: The Death of a Disease—The Inside Story of Eradicating a Worldwide Killer. Amherst, N.Y.: Prometheus Books, 2009.

Hildreth, C. “Smallpox.” Journal of the American Medical Association 301 (2009): 1086.

Hopkins, Donald R. The Greatest Killer: Smallpox in History. Chicago: University of Chicago Press, 2002.

Koplow, David A. Smallpox: The Fight to Eradicate a Global Scourge. Berkeley: University of California Press, 2003.

Plotkin, Stanley A., Walter A. Orenstein, and Paul A. Offit. Vaccines. 5th ed. Philadelphia: Saunders/Elsevier, 2008.

Tucker, Jonathan B. Scourge: The Once and Future Threat of Smallpox. New York: Atlantic Monthly Press, 2001.

Williams, Gareth. Angel of Death: The Story of Smallpox. New York: Palgrave Macmillan, 2010.