Espul Carlos, Benedetti Laura, Cuello Héctor, Houillon Guy, Rasuli Anvar
Programa de Lucha Contra las Hepatitis Virales, Ministerio de Salud/Hospital Central de Mendoza, Mendoza, Argentina.
Programa Provincial de Inmunizaciones, Ministerio de Salud, Mendoza, Argentina.
Hepat Med. 2012 Aug 28;4:53-60. doi: 10.2147/HMER.S33847. eCollection 2012.
This study was done to determine the immunogenicity of a single dose of hepatitis A vaccine in children, providing needed clinical data on the flexibility of booster administration.
Participants had received one dose of inactivated hepatitis A vaccine (Avaxim™ 80 U Pediatric) at 12-23 months of age or two doses of the same vaccine at 12 and 18 months of age prior to enrolment. Anti-hepatitis A antibody concentrations were measured at the first, second, and third year after vaccination. Suspected cases of hepatitis A in participant families were assessed and family socioeconomic data were collected.
A series of 546 participants were enrolled. Of 467 (85.5%) participants completing 3 years of follow-up, 365 had received a single vaccine dose and 94 had received two vaccine doses. Seropositivity (anti-HAV ≥ 10 mIU/mL) at 3 years was 99.7% after one dose and 100% after two doses. At one year, geometric mean concentrations were higher after two doses (1433.9 mIU/mL, 95% confidence interval [CI] 1108-1855) than one (209.7 mIU/mL, 95% CI 190.6-230.6). Geometric mean concentrations decreased in both groups during the study, but remained well above 10 mIU/mL through the third year. The geometric mean of 3-year to one-year anti-hepatitis A concentration ratios was 0.74 (95% CI 0.70-0.79) following one dose and 0.57 (95% CI 0.47-0.70) following two doses. The greatest decrease in geometric mean concentrations occurred during the third year, ie, 21.2% in the one-dose group and 40.8% in the two-dose group. Six participants became seronegative during follow-up and responded strongly to a booster dose. Anti-hepatitis A concentrations increased in 135 children (34.9%) in the second year and 50 (13.7%) in the third year; none lived in a family with a case of hepatitis A. Three confirmed cases of hepatitis A occurred in family members. Participants belonged to a middle-income, urban/suburban population with good sanitation facilities and water supplies.
A single dose of hepatitis A vaccine at 12-23 months of age resulted in hepatitis A seropositivity in all but one vaccinee after 3 years. Increased anti-hepatitis A serum concentrations suggested exposure to wild-type hepatitis A virus in this middle-class socioeconomic environment. Continuing surveillance is required to confirm the effectiveness of a single-dose hepatitis A vaccination; however, the results of the first three years are encouraging.
本研究旨在确定儿童单剂甲型肝炎疫苗的免疫原性，提供关于加强免疫接种灵活性的所需临床数据。
参与者在入组前12至23个月龄时接种过一剂灭活甲型肝炎疫苗（Avaxim™ 80 U儿科剂型），或在12和18个月龄时接种过两剂相同疫苗。在接种疫苗后的第一、第二和第三年测量抗甲型肝炎抗体浓度。对参与者家庭中疑似甲型肝炎病例进行评估，并收集家庭社会经济数据。
共纳入546名参与者。在完成3年随访的467名（85.5%）参与者中，365名接受了单剂疫苗，94名接受了两剂疫苗。单剂接种后3年的血清阳性率（抗-HAV≥10 mIU/mL）为99.7%，两剂接种后为100%。在1年时，两剂接种后的几何平均浓度（1433.9 mIU/mL，95%置信区间[CI] 1108 - 1855）高于单剂接种（209.7 mIU/mL，95% CI 190.6 - 230.6）。在研究期间，两组的几何平均浓度均下降，但在第三年时仍远高于10 mIU/mL。单剂接种后3年至1年抗甲型肝炎浓度比值的几何平均值为0.74（95% CI 0.70 - 0.79），两剂接种后为0.57（95% CI 0.47 - 0.70）。几何平均浓度下降幅度最大的是在第三年，即单剂接种组为21.2%，两剂接种组为40.8%。6名参与者在随访期间血清学转为阴性，并对加强剂量有强烈反应。抗甲型肝炎浓度在第二年增加的有135名儿童（34.9%），第三年增加的有50名（13.7%）；他们均无家庭成员感染甲型肝炎。家庭成员中发生了3例确诊的甲型肝炎病例。参与者属于卫生设施和供水良好的城市/郊区中等收入人群。
12至23个月龄时单剂接种甲型肝炎疫苗，3年后除一名接种者外所有接种者均呈甲型肝炎血清阳性。抗甲型肝炎血清浓度增加表明在这种中产阶级社会经济环境中接触过野生型甲型肝炎病毒。需要持续监测以确认单剂甲型肝炎疫苗接种的有效性；然而，前三年的结果令人鼓舞。
