INTRODUCTION: Hepatitis B virus (HBV) infection is a highly endemic in Mongolia. Consequently, complications of HBV including livercirrhosis and primary hepatocellular carcinoma, are crucial public health problems in the country. Since 1991, hepatitisB vaccination has been an integrated part of Mongolia’s Expanded Programme of Immunization (EPI). Since the HBVvaccination program has been implemented in Mongolia, there are few studies of HBV prevalence among children, itis essential to assess the effectiveness of HBV vaccination through the prevalence of hepatitis B virus carriage (i.e.,HBsAg) among children in Ulaanbaatar.GoalTo assess prevalence of HBV carriage and vaccination coverage among 4-6 year-old children in UlaanbaatarMATERIAL AND METHODS:∎ A representative, population based cross-sectional study was implemented in Ulaanbaatar.∎ A retrospective descriptive study design was used to estimate the HB vaccination coverage among 4-6 year-oldchildren in Ulaanbaatar.∎ A total of 2200 children, ages 4 to 6 years, were sampled using a stratified conducted, with stratified, multistage,random cluster design from 40 sub districts of 5 districts in Ulaanbaatar.∎ The children, aged 4 to 6 years, (n=1988) were tested for serological marker of HBV HBsAg.∎ All data (dose, species, and date) of the HepB vaccination were collected from the immunization record of thechildren.∎ Closed and open ended questionnaires were asked by parents to assess some social and demographicfactors.RESULT:Of the 2200 children sampled 183 children were not present at their home address and 29 children refused to participatein the study. Thus, 1988 children participated from Ulaanbaatar city (353 of from Khan-Uul district, 440 from Bayanzurkhdistrict, 400 from Bayangol district, 344 from Sukhbaatar district, 451 from Songinokhairhan district) (Response proportion90.3 percent). The mean age of children was 4.97±0.8 years with a range of 4-6 years; 1023(51%) were boys. Rapidtest results are available for all 1988 children; 0.3 percent (n=6) of whom were HBsAg carriers. HBsAg prevalence of4,5 and 6 year-old children were 0.15 percent, 0.43 percent and 0.32 percent, respectively. No association betweengender and HBsAg was identified. The administration of HB vaccine birth dose, HepB2 and HepB3 were 98.2 percent,94 percent, and 91 percent, respectively. Among children with immunization cards, 1089 (81.5 percent) children werecompletely vaccinated, 237 (17.7 percent) incompletely vaccinated and 11(0.8 percent) not vaccinated with hepatitisB vaccine. Prevalence of HBsAg carriage among children with immunization record was 0.18 percent and withoutimmunization records was 0.46 percent.CONCLUSION:Prevalence (0.31 percent) of HBV carriage among the young generation meaningfully declined compared with those ofprevious studies in Ulaanbaatar as a result of Expanded Program of Immunization. There was no significant associationbetween age or sex and HBsAg carriers.

Background: Headache disorders are most prevalent public-health problem. Worldwide, among the adults 46% suffer from primary headache, where the migraine presents 11% and tension type headache (TTH) presents 25%. Recently, one type of the primary headache, medication overuse headache tends to increase. Nowadays, there is no sufficient study about primary headache in Mongolia. So that, it is necessary to investigate prevalence, clinical type and risk factors of the primary headache. Purpose: To study prevalence and risk factors of primary headache in Mongolia. Materials and Methods: This cross-sectional study was carried out from June to November of 2017. Participants aged 18-65 years old were randomly selected from four provinces and three districts of Ulaanbaatar city. The diagnosis of headache was made using the International Classification of Headache Disorders-3 beta. Statistical analysis was performed on SPSS-23 program. Results: A total of 2043 participants (812 men and 1231 women) were reviewed. The participant’s average age was 38.6±13.4years. 1350 (66.1%) participants reported recurrent headache within the last 1 year. Of the total study population, the prevalence rate of primary headache was 1305 (63.9%). Number of people who suffered from migraine was 494 (24.2%), significantly greater in female than male participants (p=0.0001), with most frequent attacks at age 26-45 years. The risk of migraine associated with sex, education and family history (p=0.001). 592 (29.0%) of participants had TTH, mean age of them was 37.7±5.24, significant high rate in female than men, risk of TTH depends on education and job. The medication overuse headache was diagnosed at 116 (5.7%), 29.4% in men and 70.5% in women with average of 45.6±11.4 and 43±12.7 respectively. Among the participants 38.6% used medications, 28% people had one drug, 8.5% two drugs and 2% used three or more drugs. Use of non-steroid anti-inflammatory drugs (NSAID) made up major percent in headache patients. Increased frequency of medication and multidrug affected to medication overuse headache (p=0.008). Conclusion More than half of studied population had primary headache. Migraine was in 24.2%, TTH in 29.0% of people, and associated with sex, education and family history. Use of non-steroid anti-inflammatory drugs made up major percent in headache patients.