Correct. They always have the legal right to trespass me if that bothers them. It’s their property.
Right?!
One of the problems is people have a fundamental misunderstanding of infection and transmission. It’s not a yes or no proposition, but a game of odds. Those odds are directly affected by the inoculant (how much you get dosed with) and subsequent pathogen load.
Remember also that PCR tests can be very, very sensitive, and they detect only the presence of the specified genetic sequence, not the presence of the entire pathogen. Antigen tests work differently.
Let’s say a person has had COVID, and is fully vaccinated, so they have as much “immunity” as a normal person can have.
After six months or so, the antibodies have been waning since your body initially cleared the antigens/infection, because your body is not going to waste resources on stuff it no longer needs. But your exposure/vaccination left you with very good stock of memory “B” and “T” cells.
Recall also that under normal circumstances, your innate immune system kicks in almost immediately. Skin, hair, mucus is the first line, then you get complement, white blood cells, etc. If your exposure is low enough, it could very well be that the pathogen never gets a foothold, or keeps things in check until your acquired immune system kicks in. Part of your innate immune system’s job is to poke your acquired immune system to pay attention.
Under normal circumstances, your acquired immune system takes 7-10 days to spool up. Previous exposure/vaccination drops this time to 2-3 days in a healthy person.
Now you get “exposed”. Someone with a full blown COVID infection sneezes right in your face. Now it’s a game of odds. How much inoculant did you get? 1? 10? 100? 10xe10? That’s driven by a number of factors, but that individuals pathogen load is a primary driver.
Now the game of odds begins. How many particles did you get? Was it enough to overcome your innate barriers? Was it enough to evade your innate immune system and start replicating? In the case of viruses and intracelluar parasites, are enough infected cells evading destruction to generate a significant level of pathogen replication? Is it enough to actually cause symptomatic disease? Is it enough to actually generate pathogen shed that causes any reasonable risk to others?
In highly protected individuals, that load may never reach a level that causes disease. It might not reach any level at all because your innate system trapped it. It could be the amount never reaches any clinically significant amount that would cause a spread risk.
But you do “get it” and it will show up on a test if the load is high enough or the PCR test gets lucky. You may test positive even if there is no viable organism left. The PCR only looks for genetic material, and if it latches on to one, you get lucky.
Honestly, most people would be astounded that cellular biology works at all. Everything sits in a soup of goo with chemical pathways as the wiring. If things fit together, the chances of activity are higher than something that doesn’t.