MMR antibody tests: can you rely on them?

[aliena]

My three DDs have had one MMR and have had the antibody tests which show they are immune (though at quite varying levels) However is it the case that a second MMR will not boost their immunity and that their immunity will remain at the levels they currently are even if they have it?

I just want them to have the best protection against measles that they can have.

a second MMR is likely to boost their immunity to measles, especially if they at the lower end of "protected".

Thank you. I think this is where it can get complicated for those of us without specialist knowledge. The lowest U/ml we were given was for my youngest which was 880 U/ ml and the report says that over 200 U/ml is positive. My other two tested quite a bit higher than their sister (who funnily enough had her MMR the most recently). The doctors said it was sufficient immunity but I'm still worrying.

But then two of mine got whooping cough last year and were fully vaccinated so I don't know what to think.