Smallpox in the USA


Was smallpox eliminated in the USA by vaccines?

(emphasis mine)

The CDC on smallpox vaccination (USA) in the early 20th century.

Smallpox. Smallpox is the only disease that has been eradicated. During 1900-1904, an average of 48,164 cases and 1528 deaths caused by both the severe (variola major) and milder (variola minor) forms of smallpox were reported each year in the United States (1). The pattern in the decline of smallpox was sporadic. Outbreaks of variola major occurred periodically in the first quarter of the 1900s and then ceased abruptly in 1929. Outbreaks of variola minor declined in the 1940s, and the last case in the United States was reported in 1949.

Source – Achievements in Public Health, 1900-1999 Impact of Vaccines Universally Recommended for Children — United States, 1990-1998

Plotkin and Orenstein on smallpox vaccination (USA)in the early 20th century.

However, antivaccinationist sentiment and antipathy toward compulsory measures prevailed in many states, most of which passed no legislation or prohibited compulsory vaccination. Reported cases of smallpox declined from 102,791 in 1921 to 30,151 in 1931, and between 1932 and 1939, 5000 to 15,000 cases were reported annually, with 23 to 52 deaths. During the following decade, reported cases steadily diminished, the last occurring in 1949. This progress occurred in the absence of any nationally coordinated smallpox control effort, and little is known about the extent of vaccination immunity in the country during the 1940s or about the epidemiology of smallpox. However, improved smallpox control, and eventually its elimination, is attributed by Leak (see below) to the wider availability of better refrigeration and, consequently, better preservation of the vaccine. Routine vaccination continued in the United States until 1971 as a protection in case smallpox was imported and was enforced in most states by compelling vaccination as a requirement for school entry.

Vaccines. 3rd edition. Editors – S.A. Plotkin and W.A. Orenstein. Published 1999.

J.P. Leak, Surgeon Public Health Rep. 1927 Jan 28; 42(4): 221–282.

Who are Plotkin and Orenstein?

Stanley Plotkin 

Dr. Stanley Plotkin has such a storied vaccine development career that one might say he wrote the book on vaccines. In fact, he did and his book “Vaccines”, now in its 6th edition, is the standard medical reference. Dr. Plotkin’s background reads like a roadmap of 20th century infectious disease—polio, rubella, rotavirus, rabies, and varicella (chicken pox). His career has been spent on the development of these vaccines and he now advises and influences clinical practice, academia, vaccine policy, as well as industry.

Walter Orenstein

Dr. Orenstein worked for 26 years in the Immunization Program at the Centers for Disease Control and Prevention. From 1988-2004, he was the Director of the United States Immunization Program. Dr Orenstein is a Professor of Medicine, Epidemiology, Global Health, and Pediatrics, as well as Associate Director of the Emory Vaccine Center and Director of the Emory Program on Vaccine Policy and Development


The science of Smallpox vaccination

All Hail the CDC, the ‘science’ of smallpox vaccination clearly explained.

(Emphasis mine)

Vaccinia (Smallpox) Vaccine

Recommendations of the Advisory Committee on Immunization Practices (ACIP), 2001

Vaccine Efficacy

Neutralizing antibodies induced by vaccinia vaccine are genus-specific and cross-protective for other Orthopoxviruses (e.g., monkeypox, cowpox, and variola viruses) (16–18). Although the efficacy of vaccinia vaccine has never been measured precisely during controlled trials, epidemiologic studies demonstrate that an increased level of protection against smallpox persists for 10 years (19,20). Antibody levels after revaccination can remain high longer, conferring a greater period of immunity than occurs after primary vaccination alone (3,19). Administration of vaccinia vaccine within the first days after initial exposure to smallpox virus can reduce symptoms or prevent smallpox disease (2–4).

Although the level of antibody that protects against smallpox infection is unknown, after percutaneous administration of a standard dose of vaccinia vaccine, >95% of primary vaccinees (i.e., persons receiving their first dose of vaccine) will experience neutralizing or hemagglutination inhibition antibody at a titer of >1:10 (21). Neutralizing antibody titers of >1:10 persist among 75% of persons for 10 years after receiving second doses and The level of antibody required for protection against vaccinia virus infection is unknown also. However, when lack of local skin response to revaccination with an appropriately administered and potent vaccine dose is used as an indication of immunity, <10% of persons with neutralizing titers of >1:10 exhibit a primary-type response at revaccination, compared with >30% of persons with titers although it can also indicate unsuccessful vaccination because of improper administration or less potent vaccine.