A friend of mine flew back from Japan yesterday. They were involved with providing food to the passengers quarantined on the Diamond Princess. He worked about an hour away from the cruise ship.
This friend called the Center for Disease Control before flying back and asked them if he should do anything, like maybe quarantine himself in his home; they said no. No one questioned him when be boarded the plane to the states. When he left the plane he was asked if he had traveled to China and he said no; they waved him through.
My friend feels reasonable safe, their thinking was is that since they worked a good distance from the cruise ship, they should be fine. They are quarantining themselves for the two weeks, on their own, out of their own personal sense of caution.
IMHO, the CDC should be more careful. Japan continues to see more cases show up.[1] It doesn't seem unreasonable to me that the CDC should quarantine everyone coming from Yokohoma, Japan. Especially if their work was somehow related to the quarantined cruise ship.
Science reported three days ago[0] that maybe people who directly interacted with the cruise ship maybe weren't careful enough...
"Normally, those supporting a quarantine don’t have to be quarantined themselves, presuming they use personal protection equipment (PPE)—masks, gloves, goggles, and gowns. 'But the available evidence suggests that PPE was not appropriately used on board,' Hunter says. He believes the officers who worked onboard the Diamond Princess should have been quarantined once the problems with infection control came to light. If such lax management had resulted in the infection of government officials in the United Kingdom, 'I suspect criminal proceedings would follow,' Hunter says."
[0]: https://www.sciencemag.org/news/2020/02/coronavirus-infectio...
[1]: https://www.worldometers.info/coronavirus/