Tsuda Kennosuke, Iwasaki Shiho, Horiguchi Haruko, Mori Masaaki, Nishimaki Shigeru, Seki Kazuo, Taguri Masataka, Yokota Shumpei, Ishiwada Naruhiko
Perinatal Center for Maternity and Neonate Department of Pediatrics, Yokohama City University Medical Center, Yokohama, Kanagawa 232-0024, Japan.
Pediatr Int. 2012 Feb;54(1):64-7. doi: 10.1111/j.1442-200X.2011.03505.x. Epub 2011 Dec 22.
Haemophilus influenzae type b (Hib) vaccine became available for use in Japan in December 2008. The aim of the present study was to evaluate the immunogenicity of Hib vaccine in Japanese preterm infants.
Serum samples were obtained from 54 preterm infants before the first vaccination and 1 month after the third. Anti-polyribosylribitol phosphate (PRP) antibodies were measured using an enzyme-linked immunosorbent assay method. Antibody positivity was defined as levels >1 µg/mL.
Of the 54 preterm infants, 46 (85.2%) achieved antibody levels >1 µg/mL. This compares with the 92.4% reported in full-term infants. The antibody seroconversion rate of infants starting vaccination at 2 months of age was close to being significantly lower than when vaccination was started at 3 months of age (P= 0.060). In addition, the percentage of infants achieving a positive response in the group with a history of antenatal steroid exposure was significantly higher than in those not exposed (P= 0.046). Thus, risk factors for lower Hib antibody concentrations after three doses of vaccine were age at first vaccination and lack of use of antenatal steroids.
There is a possibility that perinatal factors and the environment unique to preterm infants are related to their lower antibody positivity rates compared to full-term infants. It may therefore be preferable to modify the proposed immunization schedule.
b型流感嗜血杆菌（Hib）疫苗于2008年12月在日本开始投入使用。本研究的目的是评估Hib疫苗在日本早产儿中的免疫原性。
采集54名早产儿首次接种疫苗前及第三次接种后1个月的血清样本。采用酶联免疫吸附测定法检测抗多聚核糖基核糖醇磷酸（PRP）抗体。抗体阳性定义为水平>1μg/mL。
54名早产儿中，46名（85.2%）的抗体水平>1μg/mL。而足月儿的这一比例为92.4%。2月龄开始接种疫苗的婴儿抗体血清转化率接近于显著低于3月龄开始接种疫苗的婴儿（P=0.060）。此外，有产前类固醇暴露史的婴儿组中获得阳性反应的百分比显著高于未暴露组（P=0.046）。因此，三剂疫苗后Hib抗体浓度较低的危险因素是首次接种疫苗时的年龄和未使用产前类固醇。
与足月儿相比，围产期因素和早产儿特有的环境可能与他们较低的抗体阳性率有关。因此，可能最好修改建议的免疫接种计划。
