Francisco Nogareda1, Nyamaa Gunregjav2, Amarzaya Sarankhuu3, Enkhtuya Munkhbat2, Enkhbaatar Ichinnorov4, Pagbajabyn Nymadawa5, Kathleen Wannemuehler6, Mick N Mulders7, Jose Hagan8, Minal K Patel9. 1. World Health Organization Consultant, C/Juan de Austria, 13, 28010 Madrid, Spain. 2. National Center for Communicable Diseases, Ministry of Health, Nam Yan Ju Street 1, Ulaanbaatar, Mongolia. 3. Ministry of Health, Olympic Street 2, Government Building VIII, Ulaanbaatar, Mongolia. 4. National Statistics Office, Baga Toiruu 44, Government Building III, Ulaanbaatar, Mongolia. 5. Ministry of Health, Olympic Street 2, Government Building VIII, Ulaanbaatar, Mongolia; Mongolian Academy of Medical Sciences, Prime Minister Amar Street, Ulaanbaatar, Mongolia. Electronic address: nymadawa@gyals.mn. 6. Global Immunization Division, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA 30333, United States. Electronic address: kpw9@cdc.gov. 7. Expanded Programme on Immunization, World Health Organization, 20 Avenue Appia, 1211 Geneva, Switzerland. Electronic address: muldersm@who.int. 8. Global Immunization Division, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA 30333, United States; Expanded Programme on Immunization, World Health Organization Regional Office of the Western Pacific, P.O. Box 2932, 1000 Manila, Philippines. Electronic address: esp3@cdc.gov. 9. Expanded Programme on Immunization, World Health Organization, 20 Avenue Appia, 1211 Geneva, Switzerland. Electronic address: patelm@who.int.
Abstract
BACKGROUND: In 2015-2016, Mongolia experienced an unexpected large measles outbreak affecting mostly young children and adults. After two nationwide vaccination campaigns, measles transmission declined. To determine if there were any remaining immunity gaps to measles or rubella in the population, a nationally representative serosurvey for measles and rubella antibodies was conducted after the outbreak was over. METHODS: A nationwide, cross-sectional, stratified, three-stage cluster serosurvey was conducted in November-December 2016. A priori, four regional strata (Ulaanbaatar, Western, Central, and Gobi-Eastern) and five age strata (6 months-23 months, 2-7 years, 8-17 years, 18-30 years, and 31-35 years) were created. Households were visited, members interviewed, and blood specimens were collected from age-appropriate members. Blood specimens were tested for measles immunoglobulin G (IgG) and rubella IgG (Enzygnost® Anti-measles Virus/IgG and Anti-rubella Virus/IgG, Siemens, Healthcare Diagnostics Products, GmbH Marburg, Germany). Factors associated with seropositivity were evaluated. RESULTS: Among 4598 persons aged 6 months to 35 years participating in the serosurvey, 94% were measles IgG positive and 95% were rubella IgG positive. Measles IgG seropositivity was associated with increasing age and higher education. Rubella IgG seropositivity was associated with increasing age, higher education, smaller household size, receipt of MMR in routine immunization, residence outside the Western Region, non-Muslim religious affiliation, and non-Kazakh ethnicity. Muslim Kazakhs living in Western Region had the lowest rubella seroprevalence of all survey participants. CONCLUSIONS: Nationally, high immunity to both measles and rubella has been achieved among persons 1-35 years of age, which should be sufficient to eliminate both measles and rubella if future birth cohorts have ≥ 95% two dose vaccination coverage. Catch-up vaccination is needed to close immunity gaps found among some subpopulations, particularly Muslim Kazakhs living in Western Region.
BACKGROUND: In 2015-2016, Mongolia experienced an unexpected large measles outbreak affecting mostly young children and adults. After two nationwide vaccination campaigns, measles transmission declined. To determine if there were any remaining immunity gaps to measles or rubella in the population, a nationally representative serosurvey for measles and rubella antibodies was conducted after the outbreak was over. METHODS: A nationwide, cross-sectional, stratified, three-stage cluster serosurvey was conducted in November-December 2016. A priori, four regional strata (Ulaanbaatar, Western, Central, and Gobi-Eastern) and five age strata (6 months-23 months, 2-7 years, 8-17 years, 18-30 years, and 31-35 years) were created. Households were visited, members interviewed, and blood specimens were collected from age-appropriate members. Blood specimens were tested for measles immunoglobulin G (IgG) and rubella IgG (Enzygnost® Anti-measles Virus/IgG and Anti-rubella Virus/IgG, Siemens, Healthcare Diagnostics Products, GmbH Marburg, Germany). Factors associated with seropositivity were evaluated. RESULTS: Among 4598 persons aged 6 months to 35 years participating in the serosurvey, 94% were measles IgG positive and 95% were rubella IgG positive. Measles IgG seropositivity was associated with increasing age and higher education. Rubella IgG seropositivity was associated with increasing age, higher education, smaller household size, receipt of MMR in routine immunization, residence outside the Western Region, non-Muslim religious affiliation, and non-Kazakh ethnicity. Muslim Kazakhs living in Western Region had the lowest rubella seroprevalence of all survey participants. CONCLUSIONS: Nationally, high immunity to both measles and rubella has been achieved among persons 1-35 years of age, which should be sufficient to eliminate both measles and rubella if future birth cohorts have ≥ 95% two dose vaccination coverage. Catch-up vaccination is needed to close immunity gaps found among some subpopulations, particularly Muslim Kazakhs living in Western Region.
Authors: R T Chen; L E Markowitz; P Albrecht; J A Stewart; L M Mofenson; S R Preblud; W A Orenstein Journal: J Infect Dis Date: 1990-11 Impact factor: 5.226