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Number of patients enrolled with an acute respiratory illness testing positive for influenza B/Victoria and A(H1N1)pdm09 and percent of enrollees testing positive for influenza by epidemiologic week during the 2019–2020 season. Includes patients with medically attended acute respiratory illness enrolled in the US Influenza Vaccine Effectiveness network between October 29, 2019 through March 26, 2020. Dates on x-axis reflect the reported date of illness onset.
