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APHA Scientific Session and Event Listing

Recorded presentation

Dambadarjaa Davaalkham¹, Toshiyuki Ojima¹, Pagvajav Nymadawa², Ritei Uehara¹, Makoto Watanabe¹, Izumi Oki¹, and Yosikazu Nakamura¹. (1) Department of Public Health, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan, +81-285-58-7338, davaamon@jichi.ac.jp, (2) National Center for Communicable Diseases, Bayanzurkh district, Ulaanbaatar, Mongolia

Background: In Mongolia, a highly endemic country for hepatitis B virus (HBV) infection, an infant vaccination program against hepatitis B (HepB) was introduced in 1991. Our recent nationwide survey observed significantly higher prevalence of HBV infection and chronic carriage among rural children comparing to those from urban areas. Further we examined whether the administration of HepB vaccine during winter seasons play a role in these residential differences. Methods: Information regarding the socio-demographic characteristics, medical and family histories of study subjects (n=1,145; 51.7% boys; age range, 7-12 years) were obtained by parent interview. Vaccination history of each child was recorded from immunization cards at the local Health Centers. Results: Logistic regression analysis adjusting for the effects of age, sex and residence identified that winter administrations of all HepB doses were independently associated with HBV infection (Odds ratio [OR]=2.30; 95% confidence interval [CI]: 1.27-4.17) and chronic carriage state (OR=2.46; 95%CI: 0.91-6.63). Moreover, winter administration of birth HepB was associated with decreased immunity (anti-HBs alone) level induced by vaccine (OR=0.69; 95% CI: 0.45-1.05). Of note is that, after stratifying by residence, the associations between winter administration of birth HepB and vaccine induced immunity level (p=0.007) and HBV infection despite vaccination (p=0.025) were more evident for rural areas but not for urban areas (p=0.468 and p=0.388, respectively). Conclusion: The damage of HepB vaccine during the storage and transportation in harsh winter season might be playing an important role in high prevalence of HBV infection and low rate of vaccine induced immunity in rural Mongolia.

Learning Objectives:

At the conclusion of the session, the participant in this session will be able to
• Identify the risk factors for HBV infection
• Identify the associations between winter administration of Hepatitis B vaccine and HBV infection
• Discuss the urban-rural differences in the effectiveness of national vaccination program against hepatitis B

Keywords: Hepatitis B, Immunizations

Presenting author's disclosure statement:

Any relevant financial relationships? No

Recorded presentation