BOSTON (EGMN) – The recombinant hepatitis B vaccine confers as much protection when given alone as it does when given together with hepatitis B immunoglobulin to newborns of chronically infected mothers, but neither regimen is optimally effective, a study has shown.

The randomized controlled trial assessed the hepatitis B virus (HBV) status of 222 infants born to mothers who tested positive for hepatitis B surface antigen (HBsAg). The rate of protection observed in infants who received only the vaccine was statistically similar to that of infants who received the vaccine plus hepatitis B immune globulin (HBIG).

A total of 39% of the vaccine-only group and 41% of the combination group remained infection free at a minimum of 18 weeks after birth, Dr. Shiv K. Sarin reported at the annual meeting of the American Association for the Study of Liver Diseases, noting that nearly half of the babies in both groups developed occult HBV infections.

The current standard of care for preventing HBV infection in babies born to mothers who are HBsAg positive is the recombinant hepatitis B virus vaccine plus HBIG, however previous studies have suggested the possibility that the vaccine alone may be as effective as the combination therapy, said Dr. Sarin of the Institute of Liver and Biliary Sciences in New Delhi.

To test this hypothesis, Dr. Sarin, along with lead investigator Dr. Chandana Pande, a research associate at G.B. Pant Hospital in New Delhi, and colleagues randomized the newborns of 222 women who screened positive for HBsAg during their prenatal care to receive the 0.5-mL recombinant HBV vaccine at birth, 6 weeks, 10 weeks, and 14 weeks, either alone (116 infants) or with 0.5 mL intramuscular HBIG (106 infants). Mothers on antiviral therapy and those with coinfections were excluded from the investigation, he said.

All of the babies were assessed at a minimum of 18 weeks for HBsAg, HBV-DNA, and antibodies to HBsAg (anti-HBs). The study’s primary end point was freedom from overt or occult HBV infection with adequate immune response, defined as anti-HBs titers of at least 10 IU/mL, Dr. Sarin said in a poster presentation.

Babies with overt HBV infection were those whose blood specimens tested positive for HBsAg by enzyme-linked immunosorbent assay, whereas babies with occult infection were negative for HBsAg but positive for HBV-DNA by polymerase chain reaction testing, he said. Babies with no infection but whose anti-HBs titers were less than 10 IU/mL were categorized as having a poor immune response.

At 18 weeks after birth, there were no significant differences between the combination therapy group and monotherapy group with respect to the number of babies meeting the study’s primary end point, Dr. Sarin reported. Specifically, 43 babies in the combination group and 45 in the vaccine-only group remained free of overt or occult HBV infection with adequate immune response, he said.

Of the babies not meeting the primary end point, 9 had overt HBV infection, including 2 in the combination group and 7 in the vaccine-only group, and 106 developed occult HBV infection, including 52 in the combination group and 54 in the vaccine-only group, Dr. Sarin said. Neither of these differences attained statistical significance, nor did the between-group difference in the number of infants demonstrating a poor immune response, he said. Nineteen babies in the combination group and 10 in the vaccine-only group had anti-HBs titers lower than 10 IU/mL.

The large number of babies in both groups who developed occult HBV infection “may be due to intrauterine transmission of the infection,” Dr. Sarin suggested. The findings highlight the need for trials of antiviral agents during pregnancy in order to prevent cases in which immunoprophylaxis strategies need to be used, but then fail, he stressed.

Dr. Sarin and Dr. Pande said they had no relevant financial disclosures.

Copyright (c) 2010 Elsevier Global Medical News. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

波士顿(EGMN)——新德里肝胆科学研究所Shiv K. Sarin博士在美国肝病研究协会年会上报告称，单纯接种重组乙肝疫苗与合用乙肝免疫球蛋白对母亲为乙肝慢性感染者的新生儿的保护作用相似，且两者效果均不理想。

 

预防HbsAg阳性母亲的婴儿感染HBV的现行标准是接种重组乙肝疫苗加肌注乙肝免疫球蛋白(HBIG)，但此前研究显示，单纯接种疫苗可能与联合用药效果相似。为验证联合用药的保护效果，研究者对HbsAg阳性母亲的222例新生儿随机分组，分别在出生时、出生后6周、10周和14周单纯接种0.5 ml的重组HBV疫苗(116 例)或联合肌注0.5 ml的HBIG(106 例)。排除母亲接受抗病毒药物治疗以及存在合并感染者。在出生后18周对所有婴儿进行HbsAg、HBV-DNA以及抗-HBs检测。首要终点为无显性或隐性HBV感染且呈现足够的免疫反应(抗-HBs滴度≥10 IU/ml)。婴儿显性感染是指血样酶联免疫吸附试验HbsAg为阳性，而隐性感染是指HbsAg阴性但PCR检测HBV-DNA为阳性。不良免疫反应是指婴儿未感染但其抗-HBs滴度小于10 IU/ml。

 

结果显示，出生18周时，联合用药组和单纯疫苗组分别有43例和45例婴儿未见显性或阴性HBV感染且具有足够的免疫反应，两组婴儿达到首要终点的人数未见显著差异。在没有达到首要终点的婴儿中，共有9例为显性感染，其中2例出现在联合用药组，7例出现在单纯疫苗组；106例为阴性感染，联合用药组和单纯疫苗组分别有52例和54例，均无统计学意义。联合用药组和单纯疫苗组抗-HBs滴度小于10 IU/ml的婴儿数量分别为9例和10例，两组中不良免疫反应婴儿数量也未见显著差异。

 

结果表明，免疫球蛋白并不能提高乙肝疫苗对受感染母亲的新生儿的保护作用，且两种预防方案效果均不理想，有必要对免疫预防失败的感染母亲进行孕期抗病毒药物研究。

 

研究者声称无相关利益冲突披露。

 

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