Vaccine

Immunity

Although full immunity from vaccination does not last forever, some degree of protection against death from the disease may last for many years. The data published by Hanna in 1913 from an outbreak of smallpox in Liverpool, England, in 1902 to 1903, illustrated the ameliorating effect of childhood vaccination on the severity of smallpox. (22:V2:29) There was a striking difference between vaccinated and unvaccinated patients in all groups, both in the spectrum of severity and in case-fatality rates. Production decreased with age-with increasing intervals since vaccination- but was substantial even in those aged more than 50 years.

Other studies supported that vaccination had longer lasting effect than originally thought. Data collected by Mack from Western countries with importations of smallpox between 1950 and 1971 showed the case-fatality rate was 52% in never vaccinated individuals, 1.4% in those vaccinated 0-ten years before exposure, and still only 11% in those vaccinated over 20 years before exposure. (22:V2:30)

An attempt to create an attenuated vaccine in Japan proved to have dramatic reductions in adverse reactions. However, it was never able to be challenged against naturally occurring disease, since eradication programs were so successful. (22:V6:5)

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