Fig. 2From: Influenza and other respiratory viral infections associated with absence from school among schoolchildren in Pittsburgh, Pennsylvania, USA: a cohort studyCumulative attack rate, by grade and school, respectively, for all children diagnosed with influenza-like illness symptoms (ILI) a, d, those that are laboratory-confirmed with any of the respiratory viruses tested b, e, and those positive for influenza virus c, f. Lines denote binomial 95% confidence intervals. Schools are arranged by district (A1 to A3, B1 to B6)Back to article page