The only reason why you would close a border is not allow the clingons attack you and annihilate the whole human race.
I do believe though we have homo sapiens on each side of the border of the same species.
Covid is not as bad as Clingons. Clingons will kill all 26 million of us. Covid will only kill a minuscule of people with serious underlying
conditions. The only other reason to close a border is to catch a criminal on the run.