Why would rabies be a concern if nobody was bitten by the bat? That’s the only way it is transmitted.
A few reasons.
First, most people cannot tell if they've been bitten or not, as bat teeth are so small and sharp and leave a very small, almost un-detectable bite.
Second, it doesn't have to bit you. Its saliva is what carries the virus. If that saliva gets into your eye, nose or mouth as it flies over you, you can be infected.
Likewise, if it's saliva gets into a hangnail or other open wound.
Third, if you are asleep in a room where a bat is present, you'd likely never know you were bitten if you were. Nor would you know if the bat was around your mouth or eyes if you're a heavy sleeper.
Fourth, if you have kids in the house, well, same things apply.
Fifth, if you have a pet you'd never know if it had contact with the bat, especially if the bat has been in the house for a few days. If the pet hasn't been vaccinated against rabies, or is out of date, you'd never know if that pet has been exposed.
Sixth, even if your pet (and even you) are vaccinated against rabies, most veterinarians, doctors and health departments recommend your pet (and you) get rabies booster shots if you've been exposed to a rabid (or unknown) animal.
Seventh, rabies can stay dormant in a human for a year before showing any symptoms.
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Lastly, once you show symptoms, it's too late. You're going to die.
You'll never know if the bat was rabid if you let it go.
So, again, while the chances of contracting rabies is small, if you do, it's statistically 100% fatal. Only you can decide for yourself if it's worth the risk or not.