Recent reports (D Kaye.Clin Infect Dis April 1, 2008;46:iii) indicate that 2 of the 3 components of this year's influenza vaccine (Med Lett Drugs Ther 2007;49:81), the influenza B and A/H3N2 antigens, do not matchup well with circulating strains. The B component is probably not protective. The A/H3N2 antigen in the vaccine probably provides some protection, particularly for high-risk patients. The third component, the A/H1N1 antigen, is protective against circulating A/H1N1 influenza viruses, but these viruses, unlike previous A/H1N1 strains, are developing some resistance to oseltamivir (Tamiflu), particularly in Europe; in the US and Canada, about 5% of influenza A/H1N1 isolates are resistant to oseltamivir in vitro.

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