Whether it a beneficial virus or a harmful virus, it’s still a virus, and no evolutionary theory can account for that.
There are exceedingly more beneficial viruses in the human body than harmful ones.
And man is still a man.
God created, lovingly and carefully, with the capacity to ask why, unlike every other living thing on this planet.
And no, God did not create those detrimental viruses.
Did he allow them to happen?
Maybe.
Did he allow the evil of man to be expressed?
Maybe.
Is the evil in Man predetermined ? The destiny of your genes?
Can you ever know what is good, without knowing what is bad ?
Your answer of "maybe" implies that there are things which God is powerless to prevent.