Background Iranian children were vaccinated with the scheduled two doses of monovalent measles vaccine (mMV) from 1984. In December 2003, a nationwide campaign of measles-rubella (MR) immunization was established to vaccinate 5–25 year- old individuals. In 2004, the mMV was replaced with measles- mumps- rubella (MMR) vaccine. Despite the high vaccination coverage, the outbreaks of measles still occur in the country. In this Study, the MR immunity status of various age groups, vaccinated with different schedules was investigated, and the immunologic response of seronegative subjects to revaccination was examined. Methods This cross-sectional study was conducted among 7–33-year-old healthy individuals with a documented history of measles vaccination from November 2017 to June 2018. The subjects were categorized as follows: group A, including 20–33 year-old individuals; vaccinated with 1–2 doses of mMV at ages 9 and 15 months, and revaccinated with MR, group B, including 15–19-year-old individuals, vaccinated with two doses of mMV at 9 and 15 months of age, and received additional dose of MMR upon school entrance, group C, including 11–14 year-old individuals, vaccinated with two-doses of MMR at the ages of 15 months and 6 years, and group D, including 7–10 year-old individuals vaccinated with two-doses of MMR vaccine at the ages 12 and 18 months, respectively. Levels of antimeasles- antirubella IgG antibodies in the collected sera were measured. Also antimeasles- antirubella IgM and IgG of seronegative individuals were reexamined at 4–6 weeks after MMR revaccination. The collected data were analyzed using descriptive statistical methods. Results A total of 635 individuals were investigated in this study. Group A, 98; group B, 295; group C, 139; and group D, 103 persons. Overall, 12.3 and 18.4% of the population were seronegative for measles and rubella antibodies. This rate varied greatly between the 4 groups: group A, 0/0–2%; group B,15.2–25.0%; group C,11.5–17.2%; and groupD,14.6–18.4%. After revaccination, 92 and 94.9% of seronegative individuals showed IgG response to measles and rubella vaccines, respectively. Conclusion Despite the high coverage rate of M-R containing vaccines, a significant number of vaccinated subjects were seronegative for measles and rubella, possibly because of secondary vaccine failure; this may negatively affect measles-rubella elimination targets in the country. If these findings are confirmed in similar future studies, a more robust regional/national supplementary immunization activity will be considered.

Background: Iranian children have been vaccinated with the scheduled two doses of monovalent measles vaccine (mMV) since 1984. In December 2003, a nationwide campaign of measles-rubella (MR) immunization targeted 5-25 years population was established. In 2004, the mMV was replaced with measles- mumps-rubella (MMR) vaccine. Despite the high vaccination coverage, the outbreaks of measles still occurs in the country. In this Study, the measles-rubella immunity status of various age groups, vaccinated with different schedules was investigated, and the immunologic response of seronegative subjects to revaccination was examined. Methods: This cross-sectional study was conducted among 7- 33-year-old healthy individuals with a documented history of measles vaccination from November 2017-to June 2018. The subjects were categorized as fallow: groupA: including 20-33 years-old; vaccinated with 1-2 dose of mMV, and revaccinated with MR, groupB, including 15-19-year-old individuals, vaccinated with two doses of mMV at nine and 15 months of age, and in addition to one dose MMR upon school entrance, groupC, including 11-14 year-old individuals vaccinated, with two-doses of MMR at the ages of 15 months and six years, and groupD, including 7-10 year individuals vaccinated with two-doses of MMR vaccine at the ages 12 and 18 months, respectively. Nest the consecrations of antimeasles-antirubella IgG antibodies in the collected sera were measured. Among seronegative subjects, the antimeasles-antirubella IgM and IgG were reexamined at 4-6 weeks after MMR revaccination. The collected data were analyzed using descriptive statistical methods.Results: A total of 635 individuals, including 322 females were investigated in this study. The relative distribution of subjects in each group was as falows: groupA, 98; groupB, 295; groupC, 139; and groupD, 103 persons. Overall, 12.3% and 18.4% of the population were seronegative for measles and rubella antibodies. This rate varied greatly between the 4 groups: groupA, 2%-0/0%; groupB,15.2%- 25.0%; groupC,11.5%- 17.2%; and groupD,14.6%- 18.4%. After revaccination, 92% and 94.9% of seronegative individuals only showed IgG response to measles and rubella vaccines, respectively.Conclusion: Despite the high coverage rate of M-R containing vaccines, a significant numbers of vaccinated subjects were seronegative for measles and rubella, possibly because of secondary vaccine failure; this may negatively affect measles-rubella elimination targets in the country. If these findings are confirmed in similar future studies, a more robust regional/national supplementary immunization activity should be considered.

Background: In addition to scheduled 2-doses monovalent measles vaccine (mMV) immunization of Iranian children since 1984, a nationwide campaign of measles-rubella (MR) immunization among 5- 25 years-old population in December 2003 was conducted. From 2004 mMV was replaced with measles- mumps-rubella (MMR) vaccine. Despite a high vaccination coverage, outbreaks of measles occurred in the country. Study was designed to investigate seroimmunity status against measles and rubella among various age groups of population who were vaccinated with different schedule since 1984. Also, immunologic response to revaccination in seronegative subjects was evaluated. Methods: From 1 November 2017 to 30 June 2018 a cross- sectional study among 7- 33 year old (born 1984-2011) healthy population with documented history of measles vaccination was conducted. Based on their age and history of vaccination status categorized as GA: 20-2333 years old; vaccinated with 1-2 dose of mMV, and also MR revaccinated. GB: 15-19 years, vaccinated only with 2- doses of mMV at the ages of 9 and 15 months and MMR 2-5 years later. GC: 12-14 years and GD: 7-11 years; vaccinated with 2- dose of MMR vaccine at the ages 15 months - 6 years, and 12-18 months respectively. Collected sera were assessed to measure antimeasles and antirubella IgG antibodies concentration. Four to 6 weeks after revaccination of seronegative subjects, antimeasles-antirubella IgM and IgG antibodies were rechecked. Collected data were analyzed using descriptive statistical methods.Results: Totally 635 individuals, 312 female were included. Relative distribution of subjects in each group was as: GA: 98, GB: 295, GC: 139, and GD: 103 persons. Overall, 12.28% and 18.4% of population were soronegative, and varied greatly between groups: 2%-0/0%, 15.2%- 25.0%, 11.5%- 17.2%; and 14.6%-18.4%, to measles and rubella, respectively. After revaccination, 92% and 94.9% showed 1gG response to measles and rubella vaccine respectively.Conclusion: Despite high coverage rate with measles and rubella containing vaccine, a significant numbers of vaccinated subjects lost their seroprotection were seronegative, possibly because of secondary vaccine failure. This may affect measles-rubella elimination goal in the country. If these data were confirmed by further studies, more strengthen regional/ national supplementary immunization activity should be considered.

Abstract Background: In addition to schedule 2-doses monovalent measles vaccine (mMV) immunization of Iranian children since 1984, a nationwide campaign of measles-rubella (MR) immunization among 5- 25 years-old population in December 2003 was conducted. From 2004 mMV was replaced with measles- mumps-rubella (MMR) vaccine. Despite a high vaccination coverage, outbreaks of measles occurred in the country. Study was designed to investigate seroimmunity against measles and rubella among various age groups of population who were vaccinated with different schedule since 1984. Also, immunologic response to revaccination in seronegative subjects was evaluated. Methods: From 1 November 2017 to 30 June 2018 a cross- sectional study among 7- 33 year old healthy population with documented history of measles vaccination was conducted. Based on their age and history of vaccination categorized as GA: 20-23 years old; vaccinated with 1-2 dose of mMV, and also MR revaccinated. GB: 15-19 years, vaccinated only with 2- doses of mMV at the ages of 9 and 15 months. GC: 12-14 years and GD: 7-11 years; vaccinated with 2- dose of MMR vaccine at the ages 15 months - 6 years, and 12-18 month respectively. Collected sera were assessed to measure antimeasles and antirubella IgG antibodies concentration. Four to 6 weeks after revaccination of seronegative subjects, antimeasles-antirubella IgM and IgG antibodies were rechecked. Collected data were analyzed using descriptive statistical methods.Results: Totally 635 individuals, 312 female were included. Relative distribution of subjects in each group was as: GA: 98, GB: 295, GC: 139, and GD: 103 persons. Overall, 12.28% and 18.4% of population were soronegative, and varied greatly between groups: 2%-0/0%, 15.2%- 25.0%, 11.5%- 17.2%; and 14.6%-18.4% to measles and rubella, respectively. After revaccination, 92% and 94.9% showed 1gG response to measles and rubella vaccine respectively.Conclusion: Despite high coverage rate with measles containing vaccine, a significant numbers of vaccinated subjects lost their seroprotection, possibly because of secondary vaccine failure. This may affect measles-rubella elimination goal in the country. If these data were confirmed by further studies, more strengthen regional/ national supplementary immunization activity should be considered.