Vaccine
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Introduction of influenza viruses with gene segments of avian origin into the human population may result in the emergence of new pathogenic human influenza viruses. The recent infection of a 3-year-old boy with an influenza A (H5N1) virus of avian origin can be considered as an example of such an event. However, this virus, influenza A/Hong Kong/156/97 (H5N1) and the 17 additional H5N1 viruses isolated from humans by the end of 1997 lack the ability to spread efficiently amongst humans and therefore have limited pandemic potential. However, the possibility of reassortment of these viruses with currently circulating human viruses illustrates the need for pandemic preparedness.
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Comparative Study
A benefit-cost analysis of two-dose measles immunization in Canada.
In 1992, because of the limitations of the one-dose measles immunization program, the National Advisory Committee on Immunization (NACI) recommended a two-dose measles immunization program to eliminate measles. More recently, NACI recommended also a special catch-up program to prevent predicted measles outbreaks and to achieve an earlier elimination of measles. ⋯ The resulting benefit: cost ratios vary between 2.61:1 and 4.31:1 depending on the strategy used and the age of the children targeted. Given the parameters established for this analysis, the benefits of a second-dose vaccination program against measles far outweight the costs of such a program under all scenarios.