Our DS had his single measles jab on saturday and we were given the general advice of may develop fever, rash etc and give calpol. Ive read that the vaccine takes around a week to kick in and then you get the rash/fever (in mild form mostly). However ds had mild fever over sunday and was miserable. Perked up a bit yesterday, fever gone.and he's back to usual self today. Is that it with reactions? or will he still get rash in a week. confused as expected worse next weekend