Figure 1.

Influenza detections among eligible patients presenting with influenza-like illness, by week of specimen collection, Canadian Sentinel Practitioner Surveillance Network, 4 November 2018–12 January 2019 (n = 1,518)^a

^a One specimen was co-infected with influenza A(H1N1)pdm09 and influenza B and another specimen was co-infected with influenza A(H1N1)pdm09 and A(H3N2). Viruses involved in co-infections are plotted separately by type/subtype such that specimens involved in co-infections appear twice.

^b Missing specimen collection dates were imputed as the date the specimen was received and processed at the provincial laboratory minus 2 days, the average time between specimen collection date and laboratory received date among specimens with complete information for both values. Data for week 2 may be incomplete given delays in specimen processing and laboratory testing.