In short, ME/CFS patients are older. Corvid-19 kills older people more often (over 20% in some age ranges). This computes the risk over all ages with ME/CFS. ME/CFS is not causing this high rate, patient ages are.
For reference, Flu Death Rate from CDC for 2018-2019: (=34,157/35,520,883) or 0.0962%. So the risk of death is 46.8x more
This is based on the following studies:
- The Epidemiological Characteristics of an Outbreak of 2019 Novel Coronavirus Diseases (COVID-19) – China CCDC, February 17 2020
- The prevalence of self-reported chronic fatigue in a U.S. twin registry. 
- Prevalence of chronic fatigue syndrome in metropolitan, urban, and rural Georgia. 
- The Relationship between Age and Illness Duration in Chronic Fatigue Syndrome 
- Two age peaks in the incidence of chronic fatigue syndrome/myalgic encephalomyelitis: a population-based registry study from Norway 2008-2012 
- Cardiovascular characteristics of chronic fatigue syndrome 
The methodology was to obtain the incidence rates for CFS/ME for items like:
Then obtain the ages and numbers in each age bracket with ME/CFS and then apply the following:
As of this morning, there is a very strong statistical model saying that it will go pandemic with every country severely infected. By April 1st, there may be more cases outside of China than in China.