Potentially more effective than Tamiflu, a new vaccine to prevent bird flu in humans has been developed by Chinese scientists.

Like Tamiflu, manufactured by Switzerland-based Roche, the new vaccine is a neuraminidase inhibitor, which hinders the enzyme neuraminidase, thus preventing the virus from transferring from cell to cell.

 

But its molecule structure is different from Tamiflu's.

 

"We have completed clinical experiments, and find it is more effective on humans than Tamiflu," said Li Song, a leading scientist with a research group based at the Academy of Military Medical Sciences.

 

Yesterday, at a high-profile forum on prevention and control of avian influenza, Li went on to explain that the cost of the new drug is only a quarter to a third that of Tamiflu, which in China currently sells for 29.8 yuan (US$3.73) per capsule.

 

He added the new drug would be produced by domestic companies and stockpiled only for contingency use in battling a pandemic outbreak of the deadly strain of the H5N1 bird flu virus.

 

Tamiflu is the only drug acknowledged worldwide as being effective against human infections and it is being stockpiled by governments for possible use in a pandemic.

 

On December 12, Shanghai Pharmaceutical Group (SPG) became the first company in Asia to secure a license from Roche for the production of a generic variety of Tamiflu. The license allows SPG to produce and sell the drug, known generically as oseltamivir, on the Chinese mainland.

 

Li's team is also working on an injection formula which can be used for emergency treatment. "Patients in critical condition can hardly take oral medication. Also, injections are more efficacious than oral medication like Tamiflu or the new drug," Li said.

 

Li explained that all medicines for human infections are basically best for prevention rather than treatment, because "bird flu knocks men off so quickly." For example, Tamiflu is effective only if taken within 48 hours after contracting the virus.

 

The fatality rate for human infections is about 50 percent, and patients usually die within a week after being infected.

 

Amantadine and rimantadine are also used in China against human infections. While neither is recommended any longer by the World Health Organization, as the virus has developed resistance in some countries. But "they are still effective in China," said Chen Hualan, the nation's top veterinarian from the Harbin Veterinary Research Institute, the only such institution involved in bird flu research.

 

In the past week, China has announced several breakthroughs in the battle against bird flu. On Saturday, scientists at Chen's laboratory announced the development of the world's first live vaccine against bird flu and Newcastle disease, two killer infections for poultry. And last week, clinical trials began for a human vaccine against H5N1 and Beijing-based Sinovac Biotech Co Ltd, which developed the vaccine, said the exercise may last a year.

 

Yin Weidong, managing director of Sinovac, said China would need 200 million doses of the vaccine. "It is better to build up the production capacity of seasonal vaccines, so that when a pandemic occurs, companies can quickly start mass production," said Yin.

 

The country has reported six human infections of bird flu. Two of those infected had died by yesterday. There have been 31 major occurrences of outbreaks among poultry.

 

The disease has hammered the domestic poultry industry with losses of more than 60 billion yuan (US$7.5 billion) between October and December, according to official figures.

 

But due to China's aggressive preventive measures, 30 out of 31 outbreak sites have been lifted out of epidemic isolation. By December 14, China had not reported a new case within the past two weeks.

 

(China Daily December 27, 2005)