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美联社:中国研究人员可能已经找到能最大量生产疫苗的方法
2006-09-08

    巴塞罗那,西班牙 中国研究人员可能已经发现了在流感大流行时可以最大量生产H5N1疫苗的途径。

    在本周四的《柳叶刀》(the Lancet)杂志上,中国研究人员详细描述了他们突破了以往疫苗领域中未解决的神秘问题:如何用廉价的佐剂生产有效的H5N1疫苗,佐剂是用来增强活性成分作用的一种疫苗组分。

    这在理论上可以增加全世界大流行流感疫苗的产量。

    世界卫生组织(WHO)一位关于大流行流感疫苗开发的特别顾问Klaus Stohr博士说:“制备大流行流感疫苗中的一个难题已经被发现,中国寻求了一条被许多其他公司摈弃的道路,看来他们已经成功了。”

    到目前为止,所有利用商业化佐剂生产大流行流感候选疫苗的结果均令人失望。所有这些候选疫苗需要大剂量的抗原(疫苗的活性成分)来诱导保护性免疫反应。

    中国率先使用铝,一种未被专利保护的佐剂,很易获取。中国大流行流感候选疫苗在120个18-60岁的志愿者中进行了试验。

    大多数H5N1疫苗基于部分病毒抗原,全病毒疫苗由于引起副反应较多,在20年前就已被摈弃。

    据北京科兴(Sinovac)公司CEO尹卫东先生介绍,自2004年以来,中国研究人员一直在开发一种应对流感大流行的全病毒疫苗,这有助于节约抗原。中国研究人员在他们的研究结果中没有报告任何显著的副反应。

    匈牙利和日本也采用了相似的全病毒技术,结果也类似。

    英国莱斯特皇家医院传染病部Dr.Iain Stephenson在《柳叶刀》评论中写道:“这些发现确定了可能的剂量节约原则,这对于全球的大流感疫苗供应至关重要。”

    中国将继续进行临床和安全性试验,测试实验结果是否可以在更多人群中得到证实,并检验疫苗的安全性。尹说北京科兴(Sinovac)将在老年人和儿童中测试疫苗,这些人群的免疫系统与健康成年人有些微差异。

    中国在这样一个公共论坛上共享研究结果使得其它疫苗厂家可以从他们的工作中受益。今年,世界卫生组织承认,共有17家厂家在进行有关大流行流感疫苗的23项临床试验。而且,中国在6月份结束的临床试验,其结果在这么短的时间内就发表了,这非常不寻常。例如,另外一个有GSK研发的疫苗也在7月份获得了结果,但是他们至今仍未与世界卫生组织共享数据。

    《柳叶刀》杂志发表中国的H5N1疫苗数据与他们国家不愿意共享禽流感病毒形成鲜明的对比。世界卫生组织中国代表Henk Bekedam博士说,中国虽然共享了从人身上分离的禽流感病毒,但是却没有共享从动物身上分离的病毒。Bekedam 说,“他们虽然没有说不共享,但是我们至今没有收到病毒”,而在今年三月份中国已经签署了共享H5N1病毒的协议。

    追踪病毒,不仅仅是那些成为大流行流感疫苗病毒株的病毒,对于中国和世界来说都非常重要。Bekedam 说“现在我们怀疑病毒正在转变为更危险的形态,因此必须迅速地共享数据,使得可以制备出相应的疫苗”。“各个国家需要认识到,共享病毒是个对大家都有益的事,因为它可以促进疫苗的研发。”

    从大流行流感病毒被鉴定开始,任何疫苗大量获得都需要近一年的时间。“在大流行中,有效的疫苗将是最重要的医疗工具”,Stohr说,“但是肯定不足以用于每一个人。”

原文:
Chinese researchers may have found way to maximize vaccine production
The Associated Press
WEDNESDAY, SEPTEMBER 6, 2006

BARCELONA, Spain Chinese researchers may have found a way to create a potential H5N1 vaccine that would maximize production in the event of an influenza pandemic.

In Thursday's Lancet, researchers detailed how they cracked a previously unsolved mystery in the vaccine world: How to produce an effective H5N1 vaccine with a cheap adjuvant, a vaccine component used to stretch the active ingredient.

This could theoretically increase the number of pandemic vaccine doses worldwide.

"An important piece of the puzzle in making pandemic vaccine has been found," said Dr. Klaus Stohr, a special advisor on pandemic influenza vaccine development at the World Health Organization. "The Chinese have pursued a road abandoned by many other companies, and it looks like they may have succeeded," said Stohr.

To date, all pandemic candidate vaccines using commercially available adjuvants have been disappointing. All have required large doses of antigen, a vaccine's active ingredient, to provoke a protective immune response.

The Chinese initiative uses alum, an adjuvant that is not protected by intellectual property rights, and is readily available. The Chinese pandemic vaccine candidate was tested in 120 volunteers, aged 18-60 years.

Most H5N1 vaccines are based on partial viruses. The practice of using whole virus vaccines was abandoned more than two decades ago, due to the number of side effects they caused.

Since 2004, Chinese researchers have been developing a possible pandemic vaccine with a whole virus, which helps save the amount of antigen used, according to Dr. Weidong Yin, CEO of Sinovac Biotech, the vaccine's manufacturer. The Chinese have not reported any significant side effects in their results.

Similar techniques, also using inactivated whole viruses, have been employed in Hungary and Japan, with comparable results.

"These findings identify a potential dose-sparing approach that could be crucial for a global supply of pandemic vaccine," wrote Dr. Iain Stephenson, of the Infectious Diseases Unit at Leicester Royal Infirmary, in an accompanying comment piece in the Lancet.

China will next conduct further clinical and safety trials, to see if the results can be confirmed in more people, and to verify the vaccine's safety. Yin says that Sinovac intends to test the vaccine in the elderly and in children, groups whose immune systems are slightly different from those of healthy adults.

China's sharing of research in such a public forum allows other vaccine manufacturers to benefit from their work. This year, to WHO's knowledge, there are 17 companies conducting 23 clinical trials on possible pandemic vaccines. It is unusual that results would be shared so quickly following the conclusion of a clinical trial — China's tests ended only in June. For instance, encouraging results on another vaccine candidate were announced by GlaxoSmithKline in July, but they have yet to share their scientific data with WHO.

The Lancet publication of China's H5N1 vaccine data contrasts sharply with the country's noted reluctance to share bird flu viruses. While China has shared viruses isolated from humans, there is a discrepancy when it comes to animal viruses, said Dr. Henk Bekedam, WHO's representative in China. "They haven't said no to sharing, but we haven't yet received viruses," said Bekedam, referring to China's agreement to share H5N1 viruses back in March.

Tracking the virus, not just results in pandemic vaccine candidates, is crucial both for China and the entire world. "The moment we suspect the virus is changing into a more dangerous form, it has to be shared quickly so that a vaccine can be made," says Bekedam. "Countries need to recognize that virus sharing is a public good, since it may lead to vaccine development."

Still, from the moment that a pandemic virus is identified, it would be nearly one year before any significant amounts of vaccine would be available. "An effective vaccine would be the most important medical tool in a pandemic," said Stohr. "But there would definitely not be enough for everyone."