Previous population-based studies found that differences in collectin genes such as those of the Mannose-binding lectin (MBL), surfactant protein D (SP-D), and SP-A play important roles in disease severity following viral and bacterial infections (28–32); while dysfunctions in surfactant-related genes were shown to associate with severe COVID-19 (33). This evidence concerns the gene SFTPA2 and COVID-19.