History of Vaccination
The principle behind vaccination was first determined by Jenner in 1796 following the observation
that milkmaids infected with cowpox resisted infection with smallpox, i.e. that infection with a
related, but not identical virus affords protection against the natural disease. Centuries later,
that principle, applied in a global effort, resulted in the eradication of smallpox as a disease.
Immunity
Both antibody and cell-mediated immunity result from successful vaccination; greater than 95% of
primary vaccinees have detectable neutralizing antibody at a titer of 1:10 or more within 1-2 weeks
after immunization.
Evidence for a brisk cell-mediated immune response has also been detected. It is believed that
healing of the vaccinia infection is associated with intact cell-mediated or T-cell and cytokine
immune competence, and that viremia is defended by an intact antibody or B-cell immune competence.
Duration
Protection against disease following a single primary vaccination is very good for 3-5 years, begins to fade after 5 years, and is probably negligible after 20 years. In individuals who have been successfully revaccinated one or more times, it has been found that some residual immunity may persist for 30 years or longer. Although such immunity may protect against a fatal outcome, it may not protect against the development of a milder form of smallpox.
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Book on smallpox vaccination
by Edward Jenner, MD published in 1798
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