Fig. 3

Host response biomarker and clinical outcomes. “Confirmed viral infection” group refers to all patients in whom a respiratory virus was identified in their respiratory secretions (e.g. nasopharyngeal swap, bronchoalveolar lavage fluid) or increased anti-viral titres in their serum as measured by serology. “Airborne viruses detected” group refers to patients in whom a new respiratory virus was detected in the inspiratory filter or the expiratory filter. “No viruses detected” group refers to patients in whom no respiratory virus was detected in the respiratory secretions, serum or the ventilator filters. The IFI27 mRNA-expression was measured by quantitative real-time PCR, and its level is expressed as fold change (relative to GAPDH). The p values were calculated using Kruskal–Wallis test (for comparison of multiple groups). The error bars are mean plus standard deviation