Q. Is someone sees in a  permitted gathering of a few people, someone who is a sick with the apparent coronavirus symptoms, or knows that the person was sick and is probably still a carrier, and after asking nicely refuses to leave, can one call the police?
A. Horav Shlomo Miller’s opinion is that calling the police may not be an effective or fast solution at all, and it may depend on the local by laws. The fastest and best answer may be for the people just to pick themselves and leave.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller Shlit’a