Pulmonary function and radiological features four months after COVID-19: first results from the national prospective observational Swiss COVID-19 lung study.

In this study, reduced DLCO, decreased distance of 6MWT and desaturation during 6MWT were correlated to a severely impaired COVID-19 phenotype, and importantly this relationship was not confounded by age, sex, or BMI.

This findings combined with previous studies support the hypothesis that severe COVID-19 causes a medium-term decrease in DLCO, limitations in gas exchange and a spectrum of radiological features not previously reported.

The study identified DLCO %-predicted at four months as the single most important factor associated with severe/critical respiratory COVID-19 which translates into reduced walking distance and oxygen desaturation on exercise.

These results emphasize the importance of a systematic follow-up after severe and critical COVID-19, with appropriate management of pulmonary sequelae.