NPRTime MagazineHuffingtonPostなどの報道によれば、新たに米国CDCはワクチンと自閉症の関係を調べる大規模研究を実施し、その関連性がないことを見出した。
A large new government study should reassure parents who are afraid that kids are getting autism because they receive too many vaccines too early in life.

The study, by researchers at the Center for Disease Control and Prevention, found no connection between the number of vaccines a child received and his or her risk of autism spectrum disorder. It also found that even though kids are getting more vaccines these days, those vaccines contain many fewer of the substances that provoke an immune response.

The study offers a response to vaccine skeptics who have suggested that getting too many vaccines on one day or in the first two years of life may lead to autism, says Frank DeStefano, director of the Immunization Safety Office of the CDC.

To find out if that was happening, DeStefano led a team that compared the vaccine histories of about 250 children who had autism spectrum disorder with those of 750 typical kids. Specifically, the researchers looked at what scientists call antigens. An antigen is a substance in a vaccine that causes the body to produce antibodies, proteins that help fight off infections.

The team looked at medical records to see how many antigens each child received and whether that affected the risk of autism. The results, published in The Journal of Pediatrics, were unequivocal.

"The amount of antigens from vaccines received on one day of vaccination or in total during the first two years of life is not related to the development of autism spectrum disorder in children," DeStefano says.

The finding came as no surprise to researchers who study the immune system, DeStefano says. After all, he says, kids are exposed to antigens all the time in the form of bacteria and viruses. "It's not really clear why a few more antigens from vaccines would be something that the immune system could not handle," he says.

The study also found that even though the number of vaccines has gone up, the number of antigens in vaccines has gone down markedly. In the late-1990s, the vaccination schedule exposed children to several thousand antigens, the study says. But by 2012, that number had fallen to 315.

That dramatic reduction occurred because vaccines have become much more precise in the way they stimulate the immune system, DeStefano says.



この研究は、「2歳までに多くのワクチンを接種すること、あるいは一日に複数のワクチンを接種することで、自閉症につながる可能性がある」というワクチン否定論者への反論であると、CDCの予防接種安全管理室長Frank DeStefanoは言う。そのようなことが本当に起きるのか調べるために、DeStefanoは研究チームを率いて、250名の自閉症スペクトラム障害を持つ子供と、750名の普通の子供の予防接種歴を調べた。特に、研究者たちは科学者が免疫アンチゲンと呼ぶものに注目した。免疫アンチゲンは、ワクチンに含まれる物質で、感染症と戦うのを助けるタンパク質である抗体を身体に形成させる物質である。

研究チームは、それぞれの子供がどれだけ免疫アンチゲンを接種したか、それが自閉症リスクにどれだけ影響を与えたかを調べるために、医療記録を見た。The Journal of Pediatricsに掲載される結果は、明白なものだった。


[JON HAMILTON: "Number Of Early Childhood Vaccines Not Linked To Autism" (2013/03/29) on NPR]
Hardcore vaccine skeptics are unlikely to be swayed by the new research. But many worried parents should be, says Ellen Wright Clayton, a professor at Vanderbilt University who helped write a report on vaccine safety for the Institute of Medicine.

"I certainly hope that a carefully conducted study like this will get a lot of play, and that some people will find this convincing," Clayton says. That would let researchers pursue more important questions, she says.

"The sad part is, by focusing on the question of whether vaccines cause autism spectrum disorders, they're missing the opportunity to look at what the real causes are," she says. "It's not vaccines."

Institute of Medicineのワクチン安全性についての報告書執筆に協力したVanderbilt UniversityのEllen Wright Clayton教授は、筋金入りのワクチン否定論者は、新たな研究によって左右されることはほとんどない。しかし、心配している多くの親たちは安心することになると言う。

「このような注意深く実行された研究が多くの役割を演じ、少しでも納得できると思う人が出ることを切に願います。それにより、研究者たちはもっと重要な問題の探求にあたることができます。ワクチンが自閉症スペクトラム障害を起こすか否かにフォーカスすることの悲しい点は、本当の原因を見出す機会を失いことになります。本当の原因はワクチンではありません」とEllen Wright Clayton教授は言う。

[JON HAMILTON: "Number Of Early Childhood Vaccines Not Linked To Autism" (2013/03/29) on NPR]
また、自閉症支援団体であるAutism Speaksは...
Autism Speaks, a major advocacy and research group, seems ready to move beyond the vaccine issue. Geraldine Dawson, the group's top scientist, praised the new study and says the result should clear the way for research on other potential causes of autism.

These include factors like nutrition, which can affect a baby's brain development in the womb, Dawson says. Other factors could include medications and infections during pregnancy, she says, or an infant's exposure to pesticides or pollution.

"As we home in on what is causing autism, I think we are going to have fewer and fewer questions about some of these things that don't appear to be causing autism," Dawson says.

自閉症の主要な支援及び研究グループであるAutism Speaksは、このワクチン問題を越えて前進する準備ができているようだ。グループのトップの科学者であるGeraldine Dawsonは、この新たな研究を称賛し、自閉症の原因の新たな可能性の研究への道を拓くものだと言う。

「想定される原因には、子宮内での胎児の脳の発達に影響を与える可能性のある栄養状態があります。その他にも、妊娠中の薬物投与や感染症、さらには胎児が農薬や汚染物質に晒されるというのもあります。自閉症を起こしているものへと我々が近づくとともに、我々が、自閉症を超すことがない、これらのものを問うことはなくなっていくでしょう。」とGeraldine Dawsonは言う。

[JON HAMILTON: "Number Of Early Childhood Vaccines Not Linked To Autism" (2013/03/29) on NPR]

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