As someone who is/was planning a thru hike this year, I agree with the practical concerns. I would expand that to include concerns about resupply even being available. As schools are starting to shut down nationwide along with day cares, etc.. people will not be able to work. Companies will shut down also and our national supply systems will likely be impacted. So will you be able to find food at normal resupply points? Also expect that it will be possible that hotels and hotels may not be open... and if they are, do you really want to be there? I am going to turn 60 this year so I am in a higher risk group... This is NOT an easy decision. Oh, and if you knew you had the flu and went out in public anyway, you are morally responsible for any deaths you may have caused down the line... just like antivaxxers are responsible for the spread of preventable diseases and the deaths they cause by ruining herd immunity.