Predictability and Preparedness in Influenza Control
Derek J. Smith
Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK and National Influenza Center and Department of Virology, Erasmus Medical Center, Doctor Molewaterplein 50, 3015GE Rotterdam, Netherlands.
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Fig. 1. Expected pattern of spread of an uncontrolled influenza epidemic in Thailand. Time sequence (in days) of an epidemic, showing spread in a single simulation of an epidemic parameterized such that, on average, in a fully susceptible population, each person infects 1.5 others (i.e., R0 = 1.5). Red indicates presence of infected individuals, green the density of people who have recovered from infection or died. [Reprinted from (5).]
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Fig. 2. Antigenic evolution of human influenza A (H3N2) virus from 1968 to 2003. The relative positions of strains (colored shapes) and antisera (open shapes) were adjusted such that the distances between strains and antisera in the map represent the corresponding hemagglutination inhibition (HI) measurements with the least error. The periphery of each shape denotes a 0.5 unit increase in the total error and is a measure of confidence in the placement of the strain or antiserum. Strain color represents the antigenic cluster to which the strain belongs; antisera are not colored. Clusters were identified by a k-means clustering algorithm and named after the first vaccine strain in the cluster. Two letters refer to the location of isolation: HK, Hong Kong, China; VI, Victoria, Australia; TX, Texas, United States; BK, Bangkok, Thailand; SI, Sichuan, China; BE, Beijing, China; WU, Wuhan, China; SY, Sydney, Australia; and FU, Fujian, China) and the two digits refer to year of isolation. The grid represents one unit of antigenic distance (i.e., a two-fold dilution in HI titer). [Reprinted from (10).]
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