BEIJING - Chinese vaccine maker Sinovac Biotech Ltd hopes to put its H1N1 vaccine through its first clinical trial by the end of July, as pharmaceutical firms race to put vaccines against the new flu virus into commercial production.

Workers at Sinovac's laboratory in Beijing readied thousands of chicken eggs to grow the H1N1 virus on Monday, after the World Health Organization declared a pandemic last Thursday and warned governments to prepare for a long battle against the virus. [ID:nNLB765857]

On Friday, Novartis AG (NOVN.VX) said it expected its H1N1 vaccine to be available by autumn after it produced a first batch for testing and clinical trials [ID:nLB532879]. Baxter International Inc (BAX.N) said it was on full-scale production and hoped to have a commercially available A/H1N1 vaccine as early as next month.

China has recorded about 200 cases of H1N1, and is eager to prevent it from spreading among the wider population. Experts worry that if the disease becomes prevalent in China, with its huge population and uneven health services, it could mutate into something easily transmissible and far more deadly.

The most difficult part is that we are not sure about the performance of the virus seed since it is completely new to us, Sinovac's regulatory director, Gong Xuejie, told Reuters at the company's plant in northwestern Beijing.

Time is very short. We don't know whether we will be able to produce enough vaccines before the second wave of mass breakout.

Sinovac plans to apply the techniques it used in designing candidate vaccines against the more lethal H5N1 bird flu virus to produce its H1N1 vaccine.

Vaccines normally take much longer to develop and test. Novartis and Baxter have chosen cell-based culture methods, which they say is faster than traditional production methods that use chicken eggs.

Sinovac will use an inactivated virus as well as an adjuvant in its vaccine. Adjuvants are additives that increase the body's immune response while reducing the amount of antigen, or active ingredient, in each shot, its spokesman, Pearson Liu, said.

We can produce the vaccines in such a short time thanks to our research and development of human vaccines against the H5N1 influenza strain, Gong said.

We set up the platform for developing and producing H5N1 vaccines last year, and we also got approval from the State Food and Drug Administration. We just switched the virus seed this year based on the technologies and the platform we had set up.

The company, in cooperation with other Chinese pharmaceutical firms, is mass producing ingredients needed for the vaccine. Once it works out the right dosage to use and ensures safety, it will be able to kickstart mass production, officials said.

Sinovac's announcement that it would produce the vaccine lifted the company's shares by 14 percent last week. They touched their highest point in a year and a half after the WHO declared the H1N1 pandemic.

Rival Chinese and Western pharmaceutical firms also saw their shares rise due to the WHO announcement. (Editing by Rupert Winchester)