Duval Bernard, De Serres Gaston, Ochnio Jan, Scheifele David, Gîlca Vladimir
Institut National de Santé Publique du Québec, Canada.
Pediatr Infect Dis J. 2005 Jun;24(6):514-9. doi: 10.1097/01.inf.0000164705.74498.86.
Hepatitis A vaccines provide consistent, long-lasting protection and have been available for almost 10 years in Canada, but their use remains limited. It is difficult to assess their optimal utilization given that our knowledge of hepatitis A epidemiology in Canada is fragmentary. Unlike the United States, no nationwide study of hepatitis A prevalence has ever been done in Canada. Consequently we do not know the incidence of infection in children and what would be the most appropriate age for hepatitis A vaccination.
To estimate the proportion of 8- to 13-year-old children who have been infected with hepatitis A virus (HAV) and the risk factors for this infection on a nationwide scale.
Children were sampled in 10 Canadian provinces, comprising 5 regions, using random digit dialing methodology with regional stratification. Demographic data and information about risk factors for hepatitis A were collected by the telephone interviewers. Oral fluid samples were self-collected and mailed to the laboratory, where they were tested for anti-HAV IgG.
Of 6740 contacted families with a child of required age, 1688 (25%) agreed to participate and answered the questionnaire. From these, 1074 oral fluid samples were received, and 1057 could be analyzed. Anti-HAV IgG was detected in 2.7% of subjects, with variation by region from 0.8 to 3.4%. The parents of 54 subjects (5.1%) reported that their child had previously been vaccinated against HAV. Anti-HAV IgG was present in 2.0% of unvaccinated subjects, among whom antibody prevalence was 19.4% in children born in HAV-endemic countries, 6.1% in Native children and 4.2% in travelers to endemic countries. In multivariate analysis of all subjects, the presence of anti-HAV IgG was significantly associated with birth in an endemic country, travel to an endemic country, Native status (American Indian and Inuit population), female gender and vaccination against HAV. In nonvaccinated, non-Native children born in Canada who did not travel to endemic countries, anti-HAV prevalence was 1.1%.
The risk for hepatitis A during childhood is low in Canada. Almost all teenagers (>97%) would be at risk for infection in case of contact with HAV. Changes in immunization policy against hepatitis A should be considered.
甲型肝炎疫苗可提供持续、长效的保护，在加拿大已上市近10年，但疫苗的使用仍然有限。鉴于我们对加拿大甲型肝炎流行病学的了解支离破碎，很难评估其最佳利用率。与美国不同，加拿大从未进行过全国范围的甲型肝炎患病率研究。因此，我们不知道儿童感染的发病率以及甲型肝炎疫苗接种的最合适年龄。
在全国范围内估计8至13岁儿童中感染甲型肝炎病毒（HAV）的比例及其感染的危险因素。
采用随机数字拨号方法并按地区分层，在加拿大10个省（共5个地区）对儿童进行抽样。人口统计学数据以及甲型肝炎危险因素的信息由电话访问员收集。口服液体样本由儿童自行采集并邮寄至实验室，在实验室检测抗HAV IgG。
在6740个有符合年龄要求儿童的受访家庭中，1688个（25%）家庭同意参与并回答问卷。其中，收到了1074份口服液体样本，1057份可进行分析。2.7%的受试者检测到抗HAV IgG，各地区的比例在0.8%至3.4%之间。54名受试者（5.1%）的父母报告其孩子之前接种过甲型肝炎疫苗。在未接种疫苗的受试者中，2.0%检测到抗HAV IgG，其中在甲型肝炎流行国家出生的儿童中抗体阳性率为19.4%，原住民儿童中为6.1%，前往流行国家的旅行者中为4.2%。在对所有受试者的多变量分析中，抗HAV IgG的存在与在流行国家出生、前往流行国家旅行、原住民身份（美洲印第安人和因纽特人群体）、女性性别以及甲型肝炎疫苗接种显著相关。在加拿大出生、未接种疫苗、非原住民且未前往流行国家的儿童中，抗HAV阳性率为1.1%。
加拿大儿童期感染甲型肝炎的风险较低。几乎所有青少年（>97%）在接触甲型肝炎病毒时都有感染风险。应考虑改变甲型肝炎免疫政策。
