Technical measles question

[minceorotherwise]

Presumably each child's immune response is different to varying degrees?
Therefore each child's requirement for the amount of vaccine (in order to become immune) will be different
I am then presuming that the amount of vaccine or concentration of vaccine is derived from averages?
(Sorry if I am completely misunderstanding how vaccines work)
My reason for this question is that if a child has the single vaccines - why do they need two?
And do they all need two, or is the reason for two that some children are not immune after the first and they need to ensure mass coverage
Lastly (again sorry for lack of medical know-how, hence the reason for the question) - can a child develop actual measles from the jab? And if they do, presumably they then have total immunity anyway

The amount of infectious particle in the vaccine is not really that important, what matters is the child's immune status at the point of the vaccination. For example, if the child has had a recent viral infection, the body might still be generating loads of generic anti-viral substances, and therefore, the vaccine virus would not be multiplied as much and the immune response lower. From a public health perspective, it makes most sense to vaccinate everyone twice. That catches most vaccinees.

If a child had 1x measles single, the same applies. You could pay for a titer test and see whether that child is immune and if yes, a second shot is not needed. But on a public health/general vaccine recommendation scale, this would be too expensive and difficult to orchestrate.

Children with a very strong vaccine reaction (i.e. fever, rash) are likely to be immune, but children without a strong reaction (no fever, no rash) are (as far as I know) not less likely to be immune.

Thank you, that makes sense
If a child had a strong vaccine reaction, does that mean that their immune system is stronger or weaker in general?
By that I mean (if certain vaccines did overload the system and cause problems) - would the child with a strong vaccine reaction, be more likely to be adversely affected by multiple (ie 2nd single jab when not needed, or MMR)
This isn't in anyway a loaded question btw, I just want to understand the technicalties

and.....does a strong vaccine reaction (to measles for instance) mean that the child is fighting off the measles infection itself ??

If a child had a strong vaccine reaction, does that mean that their immune system is stronger or weaker in general?

I am not sure that you could generalise that (I have not come across an article looking at, say, fever after MMR in relation to number of trivial infections in a year or so).

The body has to "deal with" or "fight" the vaccine virus infection and the vaccine virus is weakened enough not to cause full blown measles.

I recently spoke to our local health protection agency, who told me that after the first dose of the mmr, 95% of people will be immune to measles.

Apparently the measles element is the most effective of the 3. They give the second dose to try to catch the last few people who were still not immune after the first and also because the other two elements have lower immunity percentages from the first dose (sorry I didn't ask the numbers for them though).

Thanks, that's really helpful info - it just got me thinking about different children's responses and levels of 'requirement' - aside from the whole debate, I'd never really thought about it from this perspective