Mitochondria health may have SOME impact regarding COVID-19, but it's not totally clear how much. There is a study here:
Impact of COVID-19 on Mitochondrial-Based Immunity in Aging and Age-Related Diseases
From the article:
Conclusions and Future Directions
There are many avenues involving mitochondria and their roles in inflammation that can offer answers as to why SARS-CoV-2 is impacting the elderly population so harshly, especially those that have comorbidities. Therefore, the role of mitochondria should not be ignored in the direction that treatment discovery takes. There are several links between aging mitochondria and weakened immunity; the avenues include over-stimulated or sustained inflammatory responses with interferon and cytokine release, regulation of fission and fusion, mitochondrial biogenesis, and interference of apoptosis and mitophagy. Many pathogens have shown a tendency to affect mitochondria as a way to influence host behavior once inside a cell by affecting these functions, from bacteria to parasites to viruses similar to the SARS-CoV-2.
SARS-CoV-2 enters the cell
via the ACE-2 receptor and sends its genetic material towards the mitochondria to influence ROS production, mitophagy, iron storage, platelet coagulability, and cytokine production stimulation. These functions are already suffering in aging patients. In those with comorbidities, the impaired mitochondrial functions amplify other issues that contribute to severe outcomes, such as ferritin storage in diabetes and increased coagulability in heart disease. This could provide a reason as to why older, comorbid patients have the most severe outcomes with COVID-19 and offer one direction for developing drug therapy.
While scientists around the world grapple with finding the definitive cure to the novel disease that is COVID-19, there are many things one can do at home to give themselves the best chance at survival. Apart from medications targeted at strengthening the mitochondria, exercise, fresh foods, breathing practices, and general preventative medicine practices can help the body protect itself.