I don't think any society, no matter how libertarian or anarchic, is going to allow people to move freely and conduct business as usual in the face of a pandemi

I don't think any society, no matter how libertarian or anarchic, is going to allow people to move freely and conduct business as usual in the face of a pandemic. As always "the right to extend one's fist ends where the nose of another begins". At the very least, individuals with the disease are endangering their fellow citizens if they don't isolate. Arguably, employers that do not make reasonable accommodations for sick employees are also guilty of public endangerment. Of course, their is always the risk that the drastic measures persist once the threat to public health dies down, but it's by no means necessary that such will be the case. Remember: even a small decrease in the growth rate of a disease spread can result in a large decrease in the total number of cases that occur.