Early research from the veterinary school at Tufts University has shown that transmission of COVID19 between humans and ferrets doesn't seem to readily occur. 29 ferrets living in household with coronavirus positive people were extensively tested, and none were positive for the virus. While this does not mean transmission between people and ferrets is impossible, it appears less likely in a normal household setting.
Laboratory ferrets were found to be susceptible to the COVID19 virus and can become sick. The difference is that laboratory ferrets are given relatively large amounts of virus directly into the nasal cavity. This large "dose" of virus is enough to allow the infection to establish.
What does this mean for ferret owners? Since we already know ferrets are also susceptible to influenza A virus, any people with respiratory symptoms should simply not handle their pet ferrets until they are well. Use masks and gloves, or have other well friends or family members take over their care.
A link to a news report of the Tufts University story can be found here:https://www.millburysutton.com/news/20200518/covid-19-from-humans-to-animals-highly-unlikely-study-at-tufts-finding