Huynh Chris, Minuk Gerald Y, Uhanova Julia, Baikie Maureen, Wong Thomas, Osiowy Carla
Viral Hepatitis and Bloodborne Pathogens, National Microbiology Laboratory, Winnipeg, MB, Canada.
Section of Hepatology, Department of Medicine, University of Manitoba, Winnipeg, MB, Canada.
Vaccine. 2017 Aug 16;35(35 Pt B):4515-4522. doi: 10.1016/j.vaccine.2017.07.040. Epub 2017 Jul 21.
Chronic hepatitis B virus (HBV) infection within the Canadian Arctic is considered endemic (>2% prevalence). Within the Arctic region of Nunavut, a vaccination program targeted at newborn infants was initiated approximately 20years ago, along with interim grade school catch-up programs, with the result that individuals born after 1980 are presumed vaccinated. This study investigates the effectiveness of these programs and is the first seroepidemiological survey to determine HBV prevalence in Nunavut in the post-vaccination era. Anonymized serum specimens scheduled for destruction following medical testing were collected between April 2013 and April 2014 from individuals granting consent. Specimens were tested for HBV antibodies, surface antigen (HBsAg), and HBV DNA to perform molecular characterization. Four thousand eight hundred and two specimens (13% of the population) were collected, with a resulting median age of 29years (range 1week to 93years). The prevalence of antibody to the HBV core protein was 9.4%; however, a 10-fold decrease in the rate of HBV exposure was noted among those born after 1980 compared to those born before (1.8% vs. 19.8%, p<0.01). HBsAg positivity was primarily documented in individuals born before 1980 (2.5%), although cases still occurred among the vaccine age cohort (0.3%). HBV subgenotype B5 (previously B6) was the most prevalent genotype observed (81.8%) indicating persistence of locally acquired infection. Vaccine-based antibody as the sole serological marker was evident in the vaccine age cohort, although the rate of decay with increasing age was much greater than predicted (less than 10% in those aged 5-19years). Nearly two decades after the advent of HBV vaccination in Nunavut, HBV prevalence has decreased to 1.2%, indicating non-endemic prevalence. However, the persistence of infection and a lower than expected prevalence of vaccine-based immunity in the vaccine age cohort will require further investigation to understand the causes and consequences.
加拿大北极地区的慢性乙型肝炎病毒（HBV）感染被视为地方病（患病率>2%）。在努纳武特地区的北极区域，大约20年前启动了一项针对新生儿的疫苗接种计划，同时开展了小学阶段的临时补种计划，因此推测1980年以后出生的人已接种疫苗。本研究调查了这些计划的有效性，并且是在疫苗接种时代后确定努纳武特地区HBV患病率的首次血清流行病学调查。在2013年4月至2014年4月期间，从同意参与的个体中收集了医学检测后预定销毁的匿名血清标本。对标本进行HBV抗体、表面抗原（HBsAg）和HBV DNA检测以进行分子特征分析。共收集了4802份标本（占人口的13%），中位年龄为29岁（范围为1周龄至93岁）。HBV核心蛋白抗体的患病率为9.4%；然而，与1980年以前出生的人相比，1980年以后出生的人HBV暴露率下降了10倍（1.8%对19.8%，p<0.01）。HBsAg阳性主要见于1980年以前出生的个体（2.5%），尽管在疫苗接种年龄组中仍有病例发生（0.3%）。HBV B5亚型（以前的B6亚型）是观察到的最常见基因型（81.8%），表明本地获得性感染持续存在。在疫苗接种年龄组中，基于疫苗的抗体作为唯一血清学标志物很明显，尽管随着年龄增长其衰减率远高于预期（5至19岁人群中低于10%）。在努纳武特地区开展HBV疫苗接种近二十年后，HBV患病率已降至1.2%，表明不再是地方病患病率。然而，感染的持续存在以及疫苗接种年龄组中基于疫苗的免疫力患病率低于预期，将需要进一步调查以了解其原因和后果。
