video: This model simulation shows how the 2009 H1N1 virus may spread in the United States if there is no vaccination intervention (top) vs. a vaccination effort that covers 70 percent of the population, with no particular age or risk group targeted (bottom). The basic reproductive number, a measure of the virus transmissibility, is 1.6. In the top panel, there is no intervention. Infected people enter the USA at the major transportation hubs continuously starting on day 0. The virus is widespread throughout country by day 70 with the epidemic peaking on day 103. In the bottom panel, the population is vaccinated with a homologously matched vaccine (which produces the optimal immune response), starting on day 30 and ending on day 135 when 70 percent of the population is covered. The epidemic is well-mitigated with spread equivalent to a mild seasonal influenza epidemic. This video relates to an article that appeared in the Sept. 10, 2009, issue of Science Express, published by AAAS. The study, by Dr. Y. Yang of the Fred Hutchinson Cancer Research Center in Seattle and colleagues, was titled, "The Transmissibility and Control of Pandemic Influenza A (H1N1) Virus." view more
Credit: [Video courtesy of Ira Longini]