Rubella is a contagious viral infection best known by its distinctive red rash. It's also called German measles or three-day measles. While this infection may cause mild symptoms or even no symptoms in most people, it can cause serious problems for unborn babies whose mothers become infected during pregnancy.

Rubella isn't the same as measles, but the two illnesses share some symptoms, including the red rash. Rubella is caused by a different virus than measles, and rubella isn't as infectious or as severe as measles.

The measles-mumps-rubella (MMR) vaccine is highly effective in preventing rubella.

In many countries, rubella infection is rare or even nonexistent. However, because the vaccine isn't used everywhere, the virus still causes serious problems for babies whose mothers are infected during pregnancy.