Rubeola is measles. Rubella used to be called German measles. Rubella in pregnant women can cause their
babies to have birth defects. So all children should
be immunized against rubella. Very few children are
likely to have a contraindication.

Rubella from Latin plural neuter of rubellus 'reddish' from ruber 'red' from PIE *reudh- 'red'. Rebellus is formed with -lus a diminuative suffix. There's also a Latin adjective rubellulus 'a little reddish'. Itsy bitsy red.

I searched for contraindications to rubella vaccination.
The only one found was sensitivity to egg proteins. The vaccine uses eggs in culture media for the virus.
Testing for sensitivty in children with history of egg
allergy is fairly simple and reliable.
'Allergy' means basically altered reactivity, meaning
liability to have severe vascular and other reactions to
exposure to a particular protein.

May I say, nuncle, how nice it is to have another well-red scholar to elucidatus with such classical grace!

Stop it, I'm blushing! But seriously, thank you, and you all, for the nice welcome you've given me.