Smallpox vaccine
The smallpox vaccine is a critical medical advancement that emerged from early practices of variolation, a method of inducing immunity by using material from infected individuals. Smallpox, caused by the Variola major virus, has a long history, believed to have originated in northern Africa around 10,000 years ago and resulting in millions of deaths globally. The modern smallpox vaccine was developed by Edward Jenner in 1796, who discovered that exposure to cowpox—an animal disease—could provide immunity against smallpox. This innovative approach replaced earlier, riskier practices and involved administering a vaccine derived from the vaccinia virus, which is related to cowpox.
Vaccination leads to the formation of a pustule that eventually heals, and while mild side effects may occur, serious complications are rare. The widespread use of the smallpox vaccine played a pivotal role in eradicating the disease, with the World Health Organization declaring smallpox officially eradicated in 1980 after a successful global vaccination campaign. Although routine vaccinations ceased in the U.S. in 1982, newer vaccines are now available for emergency use, reflecting ongoing preparedness against potential bioterrorism threats. The legacy of the smallpox vaccine highlights its transformative impact on public health and disease prevention.
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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 (FDA) authorized the production of a newer and safer vaccine to be placed in the Strategic National Stockpile (SNS)to be used in the event of a national emergency by the Centers for Disease Control and Prevention (CDC). Although there is no known or immediate threat of a biological attack using smallpox, the FDA remains prepared for an emergency response in coordination with the CDC should smallpox be used as a biological weapon. In 2023, the FDA approved a shelf-life extension of the vaccine held in the SNS.
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 1950s, 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
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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.
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“Smallpox Preparedness and Response Updates From FDA.” FDA, 22 Feb. 2023, www.fda.gov/emergency-preparedness-and-response/mcm-issues/smallpox-preparedness-and-response-updates-fda. Accessed 1 Mar. 2023.
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