evidence: Patients who have been infected by pathogens such as bacteria, fungi and viruses [including severe acute respiratory syndromes-corona virus-2 (SARS-CoV-2)], the virus that causes corona virus disease-19 (COVID-19) may experience impaired oxygen exchange and progressively worsening hypoxemia (Werth et al., 2010; Friedrich et al., 2017; Devraj et al., 2017; Cavezzi et al., 2020). This can be worsened by bacterial infections due to the infiltration of inflammatory cells, the proliferation of different cell types and the activation of oxygen-consuming enzymes (Colgan et al., 2016; Serebrovska et al., 2020; Rahman et al., 2021). Meanwhile, hypoxic microenvironments form in solid tumors when the oxygen demand of rapidly growing tumor cells exceeds the supply of surrounding blood vessels. This triggers increased production of pro-angiogenic factors in response to hypoxic stimulation, promoting tumor angiogenesis and growth (Wigerup et al., 2016; Ou and Lv, 2020). However, poor neovascularization can lead to increased hypoxia and hypoxia-generated intratumoral oxygen gradients promote tumor plasticity and heterogeneity (Popper, 2016; Arpino et al., 2017; Garcia-Bermudez et al., 2018; Jing et al., 2019). [...] Serebrovska, Z. O., Chong, E. Y., Serebrovska, T. V., Tumanovska, L. V., and Xi, L. (2020). Hypoxia, HIF-1α, and COVID-19: from pathogenic factors to potential therapeutic targets. Acta Pharmacol. Sin. 41 (12), 1539–1546. doi:10.1038/s41401-020-00554-8