Seasonal variations of microbial findings in patients with CAP during a 3-year period. A: Monthly distribution of viral findings. Each segment in the stacked bars represents the proportion of cases with a positive test relative to those with a valid test for detection of a specific virus. At least one test (PCR or serology) was demanded for a valid detection of influenza viruses (n = 266), whereas only PCR for all other viruses (n = 243). Continuous line shows the proportion of cases with a positive test of any virus relative to those with a valid test for the complete detection of viruses (n = 231). B: Pure bacterial, pure viral and viral–bacterial findings in a subset of 64 patients with complete samples collected. RSV, Respiratory syncytial virus; CAP, community-acquired pneumonia.