The Rubella virus IgG antibody test is a blood test used to detect the presence of IgG antibodies against the Rubella virus in a person’s bloodstream. IgG antibodies are produced by the immune system in response to an infection or vaccination, and their presence indicates that the person has either been vaccinated against or previously infected with the Rubella virus. This test is commonly used to determine a person’s immunity status to Rubella, which is particularly important for pregnant women as a Rubella infection during pregnancy can lead to serious birth defects. A positive test result for Rubella IgG antibodies indicates that the person is immune to the virus, while a negative result suggests that the person may not be immune and may require vaccination or further testing.