The virus is "known to enter" via the anus? That might be hypothesized by someone, but I haven't heard of any documented cases of anal transmission. Have you?
Here is one report[1] although this one is contracting it from the anus. Early in the pandemic I read about acquiring via the anus, but not sure if that was confirmed.
"Chinese scientists report evidence of an oral-fecal transmission route for COVID-19 viruses and show that, in hospitalized patients, viral RNA was found in anal swabs and in blood samples."
I.e. you find RNA in anal swabs & blood. It leaves your body that way. Which is a well-known fact, and might be very useful in population-level surveillance. It also means you should put the lid down before flushing, lest you create something lovingly known as a "toiled plume".
[1] https://www.cidrap.umn.edu/news-perspective/2020/02/studies-...