Yesterday, I speculated that the Supreme Court may hold oral arguments without spectators. Today, the Supreme Court announced that it would close to public. Here is the announcement on the Court's homepage:

Out of concern for the health and safety of the public and Supreme Court employees, the Supreme Court Building will be closed to the public from 4:30 p.m. on March 12, 2020, until further notice. The Building will remain open for official business, and case filing deadlines are not extended under Rule 30.1.

It isn't clear if the Court will partially re-open on March 23 to hold oral arguments.

SCOTUSBlog notes that the Supreme Court shuttered in October 8, 1918 during the Spanish Flu outbreak. The Court resumed arguments in November 1918.