Can one come into contact with it and simply not catch it, like when a cold just passes through and you don't get infected for some reason although you have been in close contact with someone who does, perhaps if you are in super health and fight it?
Also re. immunity are some people just naturally immune to this virus and would this immunity pass on to a child?
Eberyone has innate immunity. Your skin is part of the inate immunity. It is the innate immunity capable of dealing low level bugs of all types.
It all depends on how big the innoculum is, how fit you are at the time, how much else your immune system is dealing with. Some may deal with the original innoculum without it multiplying. Others may deal with it as a sub-clinical infection which can be transmitted. There really is a complete spectrum of possibilities. What will be will be and for the majority of the population it will just be a dose of flu that we would rather not have...but that you will get over it.
that is facinating - sorry but does "deal with the original innoculum without it multiplying" mean as I said, like pass through the body without showing symptoms. Therefore after this process one would be immune. That is quite complex and would mean that more people have had it that we would think....
I know this is quite complex if you can be bothered to expand if not I will understand
You get a couple of bugs which go into teh body. The inate immune system may be able to destroy them before they become 10's of bugs and before they cause coughs and sneezes. This would't actually be classed as an infection. Immunity as a result would be unlikely. Probably not particularly infectious (although not impossible.
The bugs get in and multiply to tens of bugs before the immune system throws them out. I would class this as a sub-clinical infection (although the former is probably strictly speaking also a sub-clinical infection). you may develop immunity in this circumstance. You may be infectious.
OR the bugs get in, and before the innate immunity kicks them out they get out of control and trigger a full blown immune esponse - including immunity. At this stage you are almost certainly symptomatic and infectious.
If you think about it the appearance of symptoms and severity is related (in part) to how many bugs there are. The more bugs the more poorly. Symptoms will tend to appear within a certain range. If your immune system can keep them below this then you will remain asymptomatic. If not you get poorly.
The same is true about being infectious. The more viral particals you have in your respiratory tract the more likely you are to sneeze them out and the more likely you are to be infectious. It is also about how may you sneeze out. You only need to sneeze out 1 viable particle to give the infection to someone else (which could occur with scenario 1 above). BUT you are much much much more likley to infect someone else if you throw out a million particles when you sneeze.
So the level of contaiousness is crudely related to where you are on the spectrum of infection. But it is also highly related to how susceptible the person picking up the bugs is too.