It is used for Determination of immune status of individuals to the measles virus. Documentation of previous infection with measles virus in an individual without a previous record of immunization to measles virus. The measles virus is one of the most highly contagious infectious diseases among unvaccinated individuals and is transmitted through direct contact with aerosolized droplets or other respiratory secretions from infected individuals. The presence of detectable IgG-class antibodies indicates prior exposure to the measles virus through infection or immunization. Individuals testing positive are considered immune to measles infection.