We would like to point out that in addition to high levels of serum levels being associated with COVID-19 severity, low levels of SP-D in the lung as measured in bronchoalveolar lavage fluid (BALF) have been reported in severe COVID-19 (5) and have been associated with an increased risk of the acute respiratory distress syndrome (ARDS) (12). This evidence concerns the gene SFTPD and COVID-19.