Pneumonia due to respiratory syncytial virus does not cause long-lasting disorders in respiratory gas transport after clinical resolution in adults. Comparison <i>vs</i>. SARS-CoV-2 pneumonia

Long-term consequences of viral pneumonia on lung function depend on virus-specific tissue injury. Persistent impairment of alveolar-blood gas transport has been described after SARS-CoV-2 pneumonia but has not been investigated following respiratory syncytial virus (RSV) pneumonia. Possible long-term effects of these two viral infections were never compared after their clinical resolution in terms of lung physiology. The aim of this paper was to compare long-term sequelae of RSV and SARS-CoV-2 pneumonia on lung function and blood gas transport. Adults (>18 years) with previous RSV or SARS-CoV-2 pneumonia were investigated after complete computed tomography scan resolution. Collected variables included demographics, body mass index, hemoglobin, SpO₂, modified British Medical Research Council dyspnea score, spirometry, diffusing capacity [diffusing capacity for carbon oxide (DLCO), carbon monoxide transfer coefficient (KCO)], single-breath diffusing capacity for nitric oxide (DLNO) and DLCO, DLNO/DLCO ratio, and lung capillary blood volume (Vc). 38 post-SARS-CoV-2 and 37 post-RSV patients were studied. Groups were comparable and showed similar spirometric values. Compared with RSV, SARS-CoV-2 patients had significantly lower SpO₂, DLCO, and KCO (p<0.01). Vc was markedly reduced (p<0.001), with a corresponding increase in the DLNO/DLCO ratio (p<0.001). Only post-RSV patients were dyspnea-free. In conclusion, viral pneumonia may cause long-lasting lung function impairment depending on virus-specific tissue damage. Unlike RSV, SARS-CoV-2 pneumonia induces a persistent reduction of lung Vc, leading to impaired gas exchange despite radiological resolution.