Timeliness of routine vaccination among children and determinants associated with age-appropriate vaccination in Mongolia.

INTRODUCTION: Routine vaccination at the recommended age is crucial to minimize the risk of acquiring vaccine preventable diseases. This study aimed to assess the proportion of children receiving routine immunization at the recommended age and determinants of timely (age-appropriate) vaccination in Mongolia. MATERIAL AND METHOD: A total of 879 eligible children aged 12-23 months were included in this study. We investigated age-appropriate administration of Bacillus Calmette-Guerin vaccine (BCG); hepatitis B vaccine (Hep B); oral polio vaccine (OPV); pentavalent vaccine; and measles, mumps, and rubella vaccine (MMR) using Kaplan-Meier method. Multilevel logistic regression with random intercept at cluster level was used to assess the determinants of age-appropriate vaccination. RESULTS: Overall, the crude vaccination coverage for routine vaccinations were above 90% for all vaccines except MMR1 which was 86.0% (95% CI, 83.6-88.2). While the first dose of almost all the vaccines given at birth; BCG, Hep B, and OPV0, were administered in a timely manner, a substantial proportion of second and third doses of these vaccines were not given in a timely manner with age-appropriate vaccination coverage ranging from 35.9% (32.8-39.1%) for MMR1 to 67.7% (64.5-70.7%) for OPV1 respectively. Factors associated with age-appropriate administration of the investigated vaccines included socio-economic status of household, religion of household heads, area of residence, owning mobile phone, and season of childbirth. For instance, children belonging to households from richer wealth quintile had higher possibilities of getting age-appropriate OPV1-OPV3, PE1-PE3 and MMR1 vaccines compared to those from the poorest household wealth quintile. CONCLUSION: Our findings suggest that the commonly used indicator 'crude vaccination coverage' could be supplemented by 'age-appropriate vaccination' to help to identify gaps in timely vaccinations and stimulate interventions in Mongolia. Factors such as household wealth quintile, place of residence and religion associated with timely vaccination in our study could be considered to promote effective intervention aiming to improve adequate vaccination coverage.

Measles and rubella IgG seroprevalence in persons 6 month-35 years of age, Mongolia, 2016.

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.

High agreement between the new Mongolian electronic immunization register and written immunization records: a health centre based audit.

INTRODUCTION: Monitoring of vaccination coverage is vital for the prevention and control of vaccine-preventable diseases. Electronic immunization registers have been increasingly adopted to assist with the monitoring of vaccine coverage; however, there is limited literature about the use of electronic registers in low- and middle-income countries such as Mongolia. We aimed to determine the accuracy and completeness of the newly introduced electronic immunization register for calculating vaccination coverage and determining vaccine effectiveness within two districts in Mongolia in comparison to written health provider records. METHODS: We conducted a cross-sectional record review among children 2-23 months of age vaccinated at immunization clinics within the two districts. We linked data from written records with the electronic immunization register using the national identification number to determine the completeness and accuracy of the electronic register. RESULTS: Both completeness (90.9%; 95% CI: 88.4-93.4) and accuracy (93.3%; 95% CI: 84.1-97.4) of the electronic immunization register were high when compared to written records. The increase in completeness over time indicated a delay in data entry. CONCLUSION: Through this audit, we have demonstrated concordance between a newly introduced electronic register and health provider records in a middle-income country setting. Based on this experience, we recommend that electronic registers be accompanied by routine quality assurance procedures for the monitoring of vaccination programmes in such settings.

Rickettsia raoultii, the predominant Rickettsia found in Mongolian Dermacentor nuttalli.

Since the year 2005, clinical patterns resembling tick-borne rickettsioses have been noticed in Mongolia. Epidemiological data regarding species of the aetiological agent, tick vector, prevalence, and distribution as well as incidence of human cases throughout Mongolia are still sparse to date. In order to identify Rickettsia species occurring in Mongolia, we investigated Dermacentor nuttalli (n=179) and Ixodes persulcatus (n=374) collected in 4 selected provinces. Rickettsia raoultii was the predominant Rickettsia (82% prevalence) found in D. nuttalli and was also detected in I. persulcatus (0.8%). The Rickettsia prevalence in D. nuttalli from different provinces varied between 70% and 97%. In addition, R. sibirica was identified in approximately 4% of D. nuttalli, but solely from Arkhanghai province. The results of this study extend the common knowledge about the geographic distribution of R. raoultii and its high prevalence in D. nuttalli. Although the pathogenicity of this Rickettsia is still unclear, it should be considered in Mongolian patients suspected of having tick-borne rickettsiosis.