Why do girls have Rubella (German measles) vaccination at aroung the age of 12 or 13?

is it painful?

It's a booster to the vaccination you got at around 1 yr old.

Rubella is a virus that attacks the respiratory tract & is usually mild; however, especially girls should receive the booster before child-bearing age because if you catch it while pregnant (in the first trimester), you could transmit it to the fetus, which could cause congenital rubella syndrome. CSR can result in serious birth defects like malformed heart, deafness, mental retardation & eye problems to name just a few. Why take the chance? The vaccine gives you life-long immunity.
Does it hurt? Yes, a little -- just like any other shot.

Recommendations by the Centers for Disease Control are for initial vaccination for MMR (Measles, Mumps, Rubella) at 12-15 months of age for all children, followed by a second dose usually administered at age 4-6 (though it can be given at any time as long as 4 weeks have elapsed since the first dose and the first dose was given at or after 12 months of age.) If you have not received a second dose, it is recommended that you get it between the ages of 11-12. This is for all children, not just girls.

Vaccinations aren't painless, but the minute or two of discomfort is FAR BETTER than getting mumps, measles or rubella as a teenager, when those childhood illnesses will be more intrusive in your life, more uncomfortable and sometimes more dangerous. Compared to that the shot is nothing. Ask for some Emla cream or other topical anesthetic before the shot if you are terrified.

i've given this vaccination a couple of times , and its just like every other shot, its like a pinch

IT HAS SOMETHING TO DO WITH WHEN YOU GET OLDER AND HAVE KIDS THEY GAVE ME MINE AT SCHOOL AT 14.

Vaccinations are bad for you!

A vaccinated person is MORE likely to get a disease than a non-vaccinated person. The whole theory of vaccination is flawed. It causes a weakening of the immune system thus making those who are innoculated more susceptible to disease.
There are so many awful side effects to vaccination that it should be considered extremely dangerous.
Just sit back and think for a while.
Is there any sense in injecting a disease directly into your bloodstream.
We have been subjected to an awful mind control program to enable the drug manufacturers to make a fortune.

The Vaccination Hoax
http://www.whale.to/b/hoax1.html