The novel coronavirus disease 2019 (COVID-19), now declared a pandemic by the WHO, is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (Wu et al., 2020; Zhou et al., 2020b), which engages angiotensin-converting enzyme 2 (ACE2) as the host entry receptor (Hoffmann et al., 2020; Zhou et al., 2020b). Lung alveolar type II epithelial cells with high ACE2 expression levels are targets for SARS-CoV-2 (Zou et al., 2020). Most COVID-19 cases exhibit mild to moderate symptoms, but some patients with pneumonia suddenly deteriorate into severe respiratory failure and require intubation and mechanical ventilation (Huang et al., 2020; Xu et al., 2020; Zhou et al., 2020a).