近日JAMA上的一则研究表明,一个剂量的疫苗就可能有效地保护婴儿和儿童,并减少H1N1病毒的传播。 该项研究将出现在1月6日出版的JAMA期刊上。

在许多国家中,2009年甲型流感(H1N1)的最初报道大多牵涉到儿童,特别是那些正在上学的儿童。根据本文作者提供的背景资料,有关的报告还表明,在目前的大流行中,那些年龄不足5岁的幼童有着很高的住院率。 “Advisory Committee on Immunization Practices目前还建议,婴儿及那些年龄在9岁或以下的儿童需要接种2个剂量的H1N1疫苗,其间隔时间至少为21天(这是基于现有的人们对该年龄组使用的季节性三价流感疫苗的经验所提出的建议)。”

University of Melbourne, Australia的Terry Nolan, M.B.B.S., Ph.D.及其同僚对接种2个剂量的某种2009年甲型流感(H1N1)疫苗的有效性与安全性进行了评估,评估的对象为居住在澳大利亚的370名健康的婴儿以及年龄在6个月至9岁不到的儿童。这些孩子被随机分入接受2个剂量(间隔21天)的疫苗接种方案的小组(剂量为15毫克或30毫克)。

文章的作者报告说:“在接种了第一个剂量的疫苗之后,在15毫克组的174名婴儿或儿童中,有161人的抗体滴度为1:40或以上(占92.5%);而在30毫克组的172名婴儿或儿童中,有168人的抗体滴度达到该水平(占97.7%)。” “所有的实验对象在接种了第2剂的疫苗后,他们的抗体滴度都达到了1:40或以上。[这意味着每个孩子都达到了足以保护不受H1N1病毒侵害的抗体滴度水平。]”研究人员写到,大部分不良反应的严重程度都在轻微至中度之间。身体对疫苗的免疫反应都很强,并与年龄、基线抗体情况以及该儿童在本研究之前是否接受过一剂季节性流感疫苗无关。

文章的作者得出结论:“我们的发现提示,接种单一剂量的15毫克的疫苗可能对儿童就已经有效了,而且他们对其的耐受性良好。该发现对疾病保护以及在更广泛的人群中降低H1N1 大流行的传播都具有正面的意义。”

生物谷推荐原始出处:

JAMA. 2010;303(1):(doi:10.1001/jama.2009.1911).

Immunogenicity of a Monovalent 2009 Influenza A(H1N1) Vaccine in Infants and Children

A Randomized Trial

Terry Nolan, MBBS, PhD; Jodie McVernon, MBBS, PhD; Maryanne Skeljo, PhD; Peter Richmond, MBBS; Ushma Wadia, MBBS; Stephen Lambert, MBBS, MAppEpid; Michael Nissen, BMedSc, MBBS; Helen Marshall, MBBS, MPH; Robert Booy, MD, MSc; Leon Heron, MBChB, MPH; Gunter Hartel, MS, PhD; Michael Lai, MBBS, MMedSc; Russell Basser, MBBS, MD; Charmaine Gittleson, MBBCh; Michael Greenberg, MD, MPH

   Context  In the ongoing influenza pandemic, a safe and effective vaccine against 2009 influenza A(H1N1) is needed for infants and children.

   Objective  To assess the immunogenicity and safety of a 2009 influenza A(H1N1) vaccine in children.

   Design, Setting, and Participants  Randomized, observer-blind, age-stratified, parallel group study assessing 2 doses of an inactivated, split-virus 2009 influenza A(H1N1) vaccine in 370 healthy infants and children aged 6 months to less than 9 years living in Australia.

   Intervention  Intramuscular injection of 15 μg or 30 μg of hemagglutinin antigen dose of monovalent, unadjuvanted 2009 influenza A(H1N1) vaccine in a 2-dose regimen, administered 21 days apart.

   Main Outcome Measures  Hemagglutination inhibition assay to estimate the proportion of participants with antibody titers of 1:40 or greater, seroconversion, or a significant antibody titer increase, and factor increase in geometric mean titer. Assessments of solicited adverse events during 7 days and unsolicited adverse events for 21 days after each vaccination.

   Results  Following the first dose of vaccine, antibody titers of 1:40 or greater were observed in 161 of 174 infants and children in the 15-μg group (92.5%; 95% confidence interval [CI], 87.6%-95.6%) and in 168 of 172 infants and children in the 30-μg group (97.7%; 95% CI, 94.2%-99.1%). Corresponding seroconversion rates were 86.8% (95% CI, 80.9%-91.0%) and 94.2% (95% CI, 89.6%-96.8%), and factor increases in geometric mean titer were 13.6 (95% CI, 11.8-15.6) and 18.3 (95% CI, 15.7-21.4). All participants demonstrated antibody titers of 1:40 or greater after the second vaccine dose. Immune responses were robust regardless of age, baseline serostatus, or seasonal influenza vaccination status. The majority of adverse events were mild to moderate in severity.

Conclusion  One 15-μg dose of vaccine was immunogenic in infants and children starting at 6 months of age and vaccine-associated reactions were mild to moderate in severity.