Vaccine
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of the reactogenicity and immunogenicity of a split and a subunit-adjuvanted influenza vaccine in elderly subjects.
A randomised, open study was carried out among an elderly population in order to compare the reactogenicity and immunogenicity of an inactivated, split virion influenza vaccine (Vaxigrip, Aventis Pasteur MSD, Lyon, France) with that of an MF59-adjuvanted, subunit vaccine (Fluad, Chiron Vaccines, Siena, Italy). Both vaccines contained the three strains: A/Sydney/5/97 (H3N2), A/Beijing/262/95 (H1N1) and B/Beijing/184/93, recommended by the WHO for the 1998-1999 influenza season. A total of 2150 subjects were vaccinated and included in the reactogenicity analysis. ⋯ For both vaccines a lower percentage of subjects achieved a seroprotective titre > or =40 against the B/Beijing/184/93. A lower antibody response against the influenza B strain was also observed in other studies conducted during the same season. In subjects 75 years of age or older, Fluad was more immunogenic than Vaxigrip for all three virus strains.
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In this paper, we examine the phenomenon of 'clustering of exemptions' to childhood vaccination, and the dangers this poses both to those exempted as well as the general population. We examine how clusters of exemptions might form through collective action as described by Thomas Schelling, and how religious groups who live in close proximity to one another can "self-select" in a way that exacerbates this phenomenon. Given the growing number of exemptions and the increasing visibility of the anti-vaccine movement, policy makers must be vigilant for dangerous clustering in order to avoid loss of herd immunity.