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United States Department of Agriculture

Agricultural Research Service

Title: Some Unanswered Questions About Vaccination (1992)

Author
item Brown, Fred - YALE UNIVERSITY

Submitted to: Federation of European Microbiological Societies Microbiology Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 29, 1992
Publication Date: N/A

Interpretive Summary: Infection with agents such as measles virus leads to protection against the disease for the lifetime of the individual. This means that an individual never gets measles twice. With some diseases such as influenza, or the common cold in humans, or foot-and-mouth disease in animals, the variability of the viruses means that an infection with one strain does not necessarily confer protection against other strains of the same virus. The reasons for this difference are discussed.

Technical Abstract: (1) Why do we only get measles once, but are constantly getting colds or influenza? Antigenic variation is the usual answer to the second part of the question. But the question I am asking is why there is antigenic variation with some agents but not with others. (2) When there is no antigenic variation, why do we remain immune for life? Is it constant re-stimulation with the same agent or a relevant epitope? Or is the agent constantly ticking over in our bodies, gently tickling our immune system? (3) Why do some of us constantly get herpes? It is known that the virus 'hides' in the nerve cells between episodes, but is there antigenic variation here too? (4) Are live vaccines actually better than inactivated vaccines? The immunity evoked by a live vaccine will clearly be more like that produced by infection with the 'natural' agent. But there is the example of the study by Bottiger which showed that even 12 years after the last inoculation of inactivated polio vaccine the neutralizing antibodies in the 18 year-old people being studied were still at a high level. Similarly, Simonsen and his colleagues have concluded that vaccination against tetanus, which consisted of primary vaccination infancy and one re-vaccination five years later, secures continuous protection to about the age of 25. Clearly it is not always necessary to use a live vaccine to evoke long-term immunological memory.

Last Modified: 11/28/2014
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