Most of the chronic illness groups I am in online have been flooded with questions from members about how this new coronavirus (which causes an infection known as COVID-19) might affect those with ME/CFS. The short answer is that we don't know for sure, but we can extrapolate from the ways that something similar, like the flu, affects people with ME/CFS.
I will mostly rely on what others have already collated and written here, but first, it's helpful to understand how the immune system in most ME/CFS patients is dysfunctional. Most of us have a Th2-dominant immune system, which means--simplistically--that our immune systems tend to over-react to viruses and allergens and under-react to bacteria. COVID-19, like the flu, is caused by a virus, so that makes it less likely that most of us with ME/CFS will catch it, though early estimates show that it may be more contagious and better at spreading that the typical flu.
However, for most of us, when we are exposed to a virus (like a cold, flu, or coronavirus), because our immune system over-responds to its presence, our usual ME/CFS immune symptoms (like flu-like aches, sore throat, swollen glands, and/or feeling feverish) worsen and we "crash." How do you tell the difference between actually catching a virus and just being exposed and crashing? Clearly, many symptoms are the same, but if you are crashing because your immune system is over-reacting, you are less likely to develop virus-specific symptoms, like congestion or (especially in the case of COVID-19) cough.
You can read more about Immune System Abnormalities in ME/CFS and also my own family's approach to dealing with Virally-Triggered Crashes. While I wrote that post with colds and the flu in mind, the approaches are the same for any kind of virus, including a coronavirus. One of the things covered in that post is how to Treat Immune Dysfunction in ME/CFS - these are ways to help normalize your immune system so it won't over-react so badly and make you crash so severely. These treatments have worked very, very well for my son and I, helping to improve our immune systems, as well as improving all symptoms. These are things you can do now to improve your immune system so it is as healthy as possible when COVID-19 hits your area. We will also definitely be stocking up on herbal antivirals (which we take daily). There is not yet any prescription antiviral medication for COVID-19 (antivirals are very specific for certain types of viruses).
For more information on COVID-19 specifically, its status, how it might affect those with ME/CFS, and what anyone can do to prevent catching it, I highly recommend Jennie Spotila's latest post, A New Virus and ME, on her excellent blog, Occupy M.E. You can always count on Jennie for meticulous research and well-written information. This post is filled with solid information and advice and is well-worth reading.
In addition, the 25% ME Group (for those with ME/CFS who are the most severe) has issued an information sheet about Coronoavirus and Those with Severe ME, written by one of the top ME/CFS doctors in the UK.
I hope that helps to answer some of your questions and ease your mind a bit. Again, the bottom line is that no one knows exactly what will happen with COVID-19 in the coming weeks and months, and no one really knows yet exactly how those with ME/CFS will respond when exposed to this coronavirus, but we can use information about the flu to make some educated guesses.