Shanghai Daily News

Chinese researchers may have found a way to create an H5N1 bird flu vaccine that would maximize production in the event of an influenza pandemic.

In yesterday's edition of the Lancet, researchers detailed how they may have solved a puzzle crucial to the large-scale production of the vaccine: How to produce an effective H5N1 vaccine with a cheap adjuvant, a vaccine component used to boost the active ingredient.

This could theoretically increase the number of vaccine doses worldwide.

"An important piece of the puzzle in making pandemic vaccine has been found," said Dr Klaus Stohr, a special adviser 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."

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 to 60.

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 Yin Weidong, CEO of Sinovac Biotech, the vaccine's manufacturer. The Chinese have not reported any major side effects.

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 commentary in the Lancet.

China will conduct further clinical and safety trials, to see if the results can be confirmed in more people, and to verify the vaccine's safety.