Immunity - Dr. A answers your questions

The last three COVID - Delta updates have triggered a LOT of questions to Dr. A, so he thought he'd answer them. The 'Theme' is your immune system. Some headings are:- How does the immune system work again?- Can you (should you) "boost" immunity?- If I'm sick and I also have autoimmunity what do I need to look out for?- My doctor told me my medication lowers my immunity, why?- You mentioned things that block or slow COVID viral uptake by our cells, how?- You said zinc needs to get into the cells to help with viral infections, how do we do that?- If I'm taking all these immune supplements will I not get COVID?- Can you explain again HOW Vitamin A&D helps with immunity?- My doctor told me vitamins A&D were potentially toxic and not to take them, why?- One more time, HOW can a fully vaccinated person still 'get' COVID?