First, for some reason the Whiteblaze discussion board is down right now.
Other sites are reporting that the National Park Service is closing access to all trails within their park systems. I specifically saw on Shenandoah National Park's FB page an announcement that they were not allowing hikers into the park. One comment stated the Park's Law Enforcement personal are considered "essential" and will be on hand to arrest trespassers.
Anyone actually know if this would apply to AT thru-hikers? I realize if you are a Northbound thru-hiker, the Shenandoah is a few weeks behind you, but Southbounders might be walking up to a closed park this morning.
If I were thru-hiking today, I'd go into stealth mode and get through the park as quickly and quietly as possible. I imagine most officials will be monitoring parking lots, buildings, and trail heads.