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. 2014 Dec 9;9(12):e114479. doi: 10.1371/journal.pone.0114479

Figure 1. Establishing Influenza Epidemic Periods.

Figure 1

The proportion of the laboratory specimens positive for influenza A (light bar) and B (dark bar) viruses among isolates submitted by the states of the Health and Human Services Southeastern Health Region 4 to the National Respiratory and Enteric Virus Surveillance System maintained by the United States Centers for Disease Control and Prevention (CDC). Data are shown for 2011/12 and 2012/13. [24] Influenza epidemic periods (horizontal bars) for each year are defined using CDC criteria [22], [23].