I thought it was an interesting lesson, because if you listen to a lot of people they think buy and hold would be relatively immune from a downturn if you just hold through the valley and don't take the paper loss.  

I just cringe when I see these folks with limit experience and capital go out and buy one or two notes.. not sure the risk/reward component is there.. any one of us that has been doing this for any amount of time will get into a deal that does not work and loses money myself included.. no one is immune.

@Mary M. people with disabilities are not immune from abiding by the contract.

My understanding is that no class was immune though some took the brunt more than others (A-class) as discussed above. 

As you probably know "A blood test, sometimes called the radioallergosorbent test, can measure your immune system's response to mold by measuring the amount of certain antibodies in your bloodstream known as immunoglobulin E (IgE) antibodies."  

Oh yeah, Bill Gates came out and stated that the Omicron Variant did a better job at building immunity than the actual vaccine did, so there's that. 

What about natural immunity.

Of course, many get so much they are pretty much immune.

Require they be up to date on immunizations and spayed or nuetered. 

After living there for a week or so, any occupant is likely to become immune to the occasional noise.