Abstract
Eight months after the mass immunization campaign of November 2015 against measles and rubella in the southeast of Iran, in order to evaluate the sero-immunity level of the people living in the mentioned region, a serosurvey study was performed. Using a multi-stage probability proportional to size cluster sampling, the sera of 1,056 participants, ranging from 15 months to 20 years old, were tested for measles and rubella IgG antibodies in the National Reference Laboratory at Tehran University of Medical Sciences, Tehran, Iran. The seroprevalence rates of antibodies against measles and rubella in the age groups below 16 years were respectively 98.4 and 93.2%. In the age group of 16 to 20 years, who was not the target of the mass immunization campaign, the said rates were respectively 91.7% and 87.4%. The herd immunity of the age groups below 16 years, who were the target of the campaign, is favourably high and reassuring both for measles and for rubella. Campaigns of supplementary vaccination play a substantial role for filling the gaps in the herd immunity.