Using nasal swabs and autopsy tissues from affected patients and animal models, researchers found that the virus blocks specific genes that use oxygen to create ATP, forcing the body to deplete finite energy reserves in the body.

More details from the paper:

In nasopharyngeal samples with declining viral titers, the virus blocked the transcription of a subset of nuclear DNA (nDNA)–encoded mitochondrial OXPHOS genes, induced the expression of microRNA 2392, activated HIF-1α to induce glycolysis, and activated host immune defenses including the integrated stress response.

More info about the OXPHOS systems:

https://www.sciencedirect.com/science/article/pii/S092544390...