Figure 1. Survival analysis model of pandemic (H1N1) 2009 virus shedding over time among infected health care personnel, Seattle, Washington, USA. Survival curves were modeled on data for 16 persons who became infected with pandemic (H1N1) 2009 virus after attending a work retreat in September 2009. A negative test result by rapid culture (black line) or real-time reverse transcription–PCR (red line) was the event of interest. Shedding duration determined by using real-time reverse transcription–PCR was significantly longer than that determined by rapid culture (p = 0.02).