Immunisation – protecting our children from disease
Box 2 | Smallpox – the eradication of a disease
Just over 200 years ago an English physician, Edward Jenner, noticed that milkmaids rarely caught smallpox. He reasoned that this was because they had previously caught a similar but relatively harmless disease, cowpox. Few people infected with cowpox subsequently caught smallpox. Jenner tested his reasoning by infecting a young boy with cowpox then exposing him to smallpox. The boy did not develop smallpox, so Jenner repeated the process with others – this was the first use of vaccination. (The word ‘vaccination’ comes from Jenner's use of cowpox; the Latin word vacca means cow.)
Smallpox has been eradicated
In recent years, smallpox vaccine made from a similar virus, the vaccinia virus, has been used worldwide and smallpox has been eliminated altogether. The last naturally-occuring occurrence of the disease was in 1977, in Somalia. The last reported death due to smallpox occurred in 1978, when a British laboratory worker died as a result of accidental exposure to the live smallpox virus kept at a research institution. The World Health Organization declared smallpox eradicated in 1980.
Stores of smallpox
Since smallpox has been eradicated as a disease, the only sources of the virus are stored in a couple of high-containment laboratories. A specialist committee of the World Health Organization (WHO) suggested destroying these stores of the virus in 1986. However, a project to look at the DNA of the virus forstalled the destruction of the stores.
Now scientists are voicing arguments for and against the elimination of the virus. The most compelling argument for the destruction of the smallpox stores is the potential for terrorists to use the virus for biological warfare. Those against the destruction of the stores want the virus samples to be maintained for study.
The late Australian scientist Professor Frank Fenner, who was chairman of the WHO committee involved in the decision, maintained that the responsible action is to destroy the virus. (Even if the virus is destroyed, doses of the smallpox vaccine will be kept.)
In 2002 WHO voted to stop the destruction of remaining smallpox virus supplies. Stock of the virus will be used for research into new treatments and vaccine, and the live virus is held under very strict biosafety regulations at only two laboratories in the world - the Centers for Disease Control and Prevention in the USA, and the State Research Center of Virology and Biotechnology in the Russian Federation. The WHO is still considering the issues surrounding the destruction of the virus stock.
Footnote:
Was Jenner unethical?
Some people think that Jenner was wrong to try deliberately to infect a young boy with smallpox. At first glance, it seems as if Jenner callously used a small child as a human ‘guineapig’.
Variolation
What Jenner did was actually not new; he carried out a practice called variolation, which was common in his time. Variolation worked this way. When a person was fit and healthy, they could be infected deliberately with smallpox because they would then have a better chance of surviving. It is quite likely that the ‘variolus matter’ (pus) was taken from people who were fairly healthy themselves, so the virus they used would probably be a weakened strain.
Certainly the method worked, and it was very popular. However, variolation was risky because people in contact with the variolated person could catch smallpox and a few variolated people got such a severe case of smallpox that they died. So while variolation was a fair bet, vaccination was a much safer bet.
What Jenner did was to treat the small boy with cowpox first, and then to variolate him in the normal way. When the boy did not develop smallpox, he knew he had found a method that was safer than variolation. At no time, then, did Jenner act in an unethical way.
Boxes
Box 1. Acquired immunity: The body's second line of defence
Box 3. The basics of making a vaccine
Box 4. WHO's Global Programme for Vaccines and Immunization
Box 5. A controversial history
Related sites
Defending
Edward Jenner (ABC radio's Ockham's Razor – 23 November
1997)
Smallpox Eradication Programme (World Health Organization)
Smallpox - What is it good for (by Debora MacKenzie Short, Sharp Science Blog,
New Scientist 19 May 2011)
Smallpox (World Health Organization)
Smallpox (Stanford University, USA)
The Science of
Immunisation: Questions and Answers (Australian Academy of Science)
Updated November 2012.