《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。
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."