Is there any way we get rid of more than Covid 19 by quarantining?

Yes, there will be a drop in flu deaths this year for example. And a rebound next year

Air quality has already been reported to be improving. You have 70-90% decrease in plane and vehicle traffic. Less boat traffic too, so water quality will improve. The earth is healing itself. ;-)

Like other diseases? I don't know what this question is asking