Response to a Monovalent 2009 Influenza A (H1N1) Vaccine

There is an urgent need for a vaccine to prevent pandemic 2009 influenza A (H1N1) infection. In this report, 95% of adult subjects had a significant immune response (hemagglutination-inhibition titer, >1:40) by day 21 after receiving a single 15-μg dose of vaccine. In this report, 95% of adult subjects had a significant immune response (hemagglutination-inhibition titer, >1:40) by day 21 after receiving a single 15-μg dose of vaccine. The rapid global spread of a novel 2009 influenza A (H1N1) virus (2009 H1N1) prompted the World Health Organization (WHO), on June 11, 2009, to declare the first influenza pandemic in 41 years. 1 In the Southern Hemisphere, 2009 H1N1 infection has been dominant during the current influenza season. 2 In the Northern Hemisphere, the incidence of 2009 H1N1 infection has increased substantially during the early part of the influenza season. The availability of safe and effective vaccines is a critical component of efforts to prevent 2009 H1N1 infection and mitigate the overall effect of the pandemic. 3 , 4 Shortly after the identification . . .