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)