HONG KONG (Reuters) - Beijing has given the go-ahead to a Chinese drug maker to begin large-scale production of a human bird flu vaccine, after a second clinical trial showed the vaccine was safe and effective, the company said on Thursday.
The vaccine uses an inactivated whole H5N1 virus from Vietnam, said an official for Sinovac Biotech, which jointly developed the vaccine with China's Centers for Disease Control.
"We finished our second trial in November. We checked our 402 participants for antibodies and they met international standards used in the United States and the European Union both for safety and immune response," Sinovac's publicity supervisor Liu Peicheng told Reuters by telephone.
China's State Food and Drug Administration said on Wednesday it had authorized production of the vaccine.
The vaccine was used in amounts of 5, 10 and 15 micrograms but the 10 microgram dose was found to be ideal.
"The 10 and 15 microgram doses met standards but we decided on 10 as it's good enough. It would use less antigen," said Liu.
Antigens are substances like toxins, viruses and bacteria that stimulate the production of antibodies when introduced into the body. But they can be difficult to culture and scientists have been trying to fix that by using boosters, or adjuvants.
Participants in the Chinese trial were between the ages of 18 and 60. Liu said only some minor side effects were recorded, in line with those sometimes seen with seasonal flu vaccines. He did not elaborate.
For years now, experts have warned of a flu pandemic and many have held up the H5N1 virus as a prime candidate because people have no immunity against this bird virus, and because of the high mortality rate associated with it so far.
The virus has infected 376 people in 14 countries since late 2003 and killed 238 of them, or 63 percent.
An eventual vaccine to protect people against a flu pandemic can only be made 4-6 months after the start of such a disaster, when the culprit virus strain has been identified.
But human populations still need some form of protection in those initial months of a pandemic, and drug companies are in a race to design what are known as "prepandemic" vaccines, which is what Sinovac is producing now.
The company is conducting tests to see if the vaccine may offer cross protection against other strains of the virus found in Indonesia, Turkey and Anhui province in China, Liu said.
"This vaccine is reserved for emergencies in the country and we have to get instructions on how much to produce," he added.
On March 2, GlaxoSmithKline company said a vaccine it designed to protect people against H5N1 may be effective in warding off a few different sub-types of the virus.
Editing by Jerry Norton