Smallpox (20th Century)

Smallpox is considered one of the deadliest human pathogenic diseases, and has been responsible for hundreds of millions of deaths worldwide. Although the virus was officially declared eradicated in 1980, repositories remain. A reintroduction of the virus into an unprotected population could cause substantial morbidity and mortality. Minimizing the impact of a smallpox outbreak requires coordination of emergency personnel, medical staff, and government officials.

According to the World Health Organization (WHO), smallpox is a highly infectious disease unique to humans, caused by either Variola major or Variola minor, with overall mortality rates of approximately 30 percent and 1 percent, respectively. Both variants are easily spread through human vapor droplets (i.e., coughing or sneezing), when inhaled by persons in close proximity.

WHO reports that between 20 and 60 percent of infected children and 80 percent of children succumb [Page 644]to smallpox. During 18th-century Europe, the disease killed an average of 400,000 persons annually.

During the 20th century, WHO estimates that smallpox was responsible for 300–500 million deaths worldwide. In the early 1950s, approximately 50 million cases occurred globally each year. As late as 1967, WHO estimates that 15 million people contracted the disease, and two million died. Vaccination campaigns were launched during the 19th and 20th centuries. The last case in the United States occurred in 1949, and vaccination against smallpox stopped in 1972. The last natural documented case occurred in Somalia in 1977, and in 1980, the WHO declared that the disease had been globally abolished. Smallpox remains the only human infectious disease to have been completely eradicated.

After eradication of smallpox in 1980, official viral stockpiles remained in two countries—the United States and the Soviet Union. Much of the former Soviet Union's supply is still unaccounted for. The terrorist attacks of September 11, 2001, and subsequent anthrax attacks renewed a concern that terrorists may attempt to obtain and use the virus against the American public. According to the U.S. Centers for Disease Control and Prevention (CDC), smallpox is viewed as a high-priority threat because of its lethality, communicability, lack of established treatment, and lack of public immunity.

A Smallpox Vaccination Program (SVP) administered by the CDC began in January 2003 in three proposed phases. Phase 1 included voluntary vaccination of front-line healthcare workers, emergency responders, selected military, and State Department personnel who could mobilize immediately following an outbreak. Phase 2 included voluntary vaccination of additional members of the healthcare and public safety communities who might be exposed. Phase 3 included voluntary vaccination of the general public.

During Phase 1, the CDC circulated guidance for the SVP, furnished educational materials, and provided vaccines to states. Over 40,000 civilian personnel in all 50 states were vaccinated. Program implementation included challenges, especially during Phase 2, such as daunting logistics, insufficient funding to states, potential disease spread into the general population, and unclear compensation guidelines to those exhibiting vaccination-related illnesses. In addition, a small number of those vaccinated suffered medical complications, especially heart problems. In mid-2003, the SVP was suspended while research continued on new and safer vaccines. Effective testing using animals has been challenging, since they do not naturally contract smallpox. In May 2007, a new vaccine was FDA approved to complete the Strategic National Stockpile. The CDC now recommends voluntary vaccination of first responders or health workers only after determination of a credible smallpox exposure or threat.

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