This is no word
definition -- this is a comment to "B.C.V."
definition.
(I have not found any other contact to write you... sorry for my ignorance.)
I think that "the time between Christ’s birth and the beginning of the coronavirus" is a constant with value 2019.
And I think that the correct definition should be "the time between an event and the beginning of the coronavirus".
Then the example "in late 2016 AD or 3 B.C.V.,
Donald Trump was elected..." will be correct.