Immune system is the protective barrier you are talking about, it only fight against the foreign bodies and it may need some time to find that solution that is what the 14 days treatment period for corona patients, and people with weak immune system may need added supplements and concentrated oxygen to ease the pain.
You can't kill a virus, all you can do is to prepare your immune system to fight against it that is what the vaccines are here for.
Ofcourse.
Not sure it's exactly what I'm talking about though. When I wrote that I was picturing many cells under the covering of transparent materials like amniotic sacs... Or imagine humans living in large transparent balloons. Humans actually have coverings like Balloons around us individually but they can't be seen with the ordinary eye. The CREATOR seems to put the covering/shield around HIS Creatures, including things as tiny as cells for their protection
I guess immunity is protection from the disease offered by our body defensive system, including the shield. While Immune System is the defensive system