It’s variable. It lasts between 14-21 days.
It’s limited. It starts 3-7 days before the eruption and stops 5-7 days after the eruption has disappeared. Newborns with congenital rubella excrete the virus for about 6-12 months, thus being highly contagious for those with whom they come in contact. In congenital rubella evolution the newborn can be contagious even 24 months.