New visitor restrictions went into effect Wednesday at New Jersey's three federal courthouses as part of an effort to stem the spread of COVID-19, also known as coronavirus.

Under an order from Chief Judge Freda Wolfson and Clerk of Court William Walsh, entry is prohibited for anyone who has been diagnosed with coronavirus, or has had contact with such a person. Also excluded from entry is anyone asked to self-quarantine by a doctor, hospital or health agency; people who have traveled within the past 14 days to countries hardest hit by the virus, including China, South Korea, Japan, Italy or Iran; those who live with or have had close contact with someone who has traveled to one of those countries within the past 14 days; or people who live with or have had close contact with someone who has been asked to self-quarantine.

Courthouse visitors are directed to report any possible exposure to the coronavirus to court security officers in the screening area before entering the courthouse, the order states.

People who have a scheduled appointment at one of the federal courts but are unable to appear for reasons related to the coronavirus are advised to contact their attorney or call one of the numbers listed on the order.

The restrictions will remain in effect until a determination is made that it is safe to remove them, the order said.

In addition, people scheduled for jury duty who seek to be excused for a medical reason must present a note from a doctor, Wolfson said in a letter to prospective jurors that was posted on the court's website Thursday.

"A general statement that you do not wish to appear because of COVID-19 will not suffice," Wolfson said.

The letter acknowledged that many people, "understandably," will have concerns about attending jury duty in a public courthouse, but said "the court is constantly and vigilantly monitoring the situation, and will take appropriate steps to make any changes in jury duty if necessary."