Seroprevalence of Measles and Rubella IgG Antibodies in Children and Pregnant Women in Iran

Complete immunization against Rubella and Measles (MR) in pediatrics is achieved using 2 doses of the Measles, Mumps, and Rubella-containing vaccine (MMR) in Iran at 12 and 18 months of age, where more than 95% of children under 5 years of age are vaccinated. Antibody waning in mothers and older children, and genetic diversity in immune responses may render them susceptible to infections.

This study aimed to investigate the diversity in immunoglobulin G (IgG) antibody levels against these two viruses in pregnant women, infants younger than 2 months, children at 6, 12, and 18 months, and 5 - 6 years of age in Iran.

This study was conducted on serum specimens sent to the National Reference Laboratory for Measles and Rubella in Tehran, Iran, from children under 2 months (n: 50), 6 (n: 54), 12 (n: 54), and 18 (n: 39) months, and 5 - 6 years old (n: 49), as well as women at 37 weeks of pregnancy (n: 53), from May to December 2020. Rubella and Measles-specific IgG were measured using an enzyme-linked immunosorbent assay kit.

Among serum samples from different provinces of Iran, the lowest positive level of Measles IgG was observed in children aged 6 and 12 months (7.41%), while the highest positive level was found in children aged 18 months (84.62%). For Rubella, the lowest IgG-positive level was seen in children aged 11 - 13 months (11.11%), while the highest positive level was observed in the 5 - 6 years old group (83.67%). Antibody levels against measles and rubella were higher in pregnant women than in children.

Measles and Rubella antibody titers were lower in children 12 months before vaccination and reached a positive level in children aged 18 months post-vaccination. Whereas, lower Measles IgG levels in 5 - 6 years old children compared to 18 months old children may be due to waning antibodies. Pregnant women exhibited high levels of protection against these viruses (more than 80% had positive rubella IgG), as anticipated from outcomes of the national vaccination program in 2004.