BEIJING — China will soon approve domestically developed swine flu vaccines that manufacturers say can protect people against the virus with only one dose, an encouraging development for health officials racing to prepare for an expected spike in cases this winter.

Many health authorities are assuming two doses of vaccine are necessary while they await the results of trials by drug makers around the world to determine the appropriate dosage.

"Everybody is desperately hoping that one will do because then that's much easier to administer," said Jodie McVernon, a vaccine expert at the University of Melbourne, who has not seen the Chinese trial results but who is involved in Australian trials of swine flu vaccines for young children.

China's State Food and Drug Administration said on its Web site it will make a decision this week on approving two vaccines that completed clinical trials last month and passed reviews by panels of about 40 experts. Four other vaccines are being reviewed, it said.

The vaccine makers, Sinovac Biotech Ltd. and Hualan Biological Engineering Inc., said the clinical trials show their products are effective in single doses when used on people aged three to 60 years. More than 3,000 people participated in the trials.

Sinovac says it has the capacity to produce up to 30 million doses of swine flu vaccine in a year while Hualan said it can make 160 million doses.

In about two weeks, the U.S. expects to announce initial test results from its vaccine, which is the same type as the Sinovac version, said Dr. Anthony Fauci of the U.S. National Institutes of Health.

"From what I've seen and heard of the data it looks encouraging," Fauci said of Sinovac's clinical trials. "This is very good news. Let's hope the material that we're using has similar results."

Stockpiling vaccines is China's latest move in its aggressive approach to contain the spread of swine flu in the country of 1.3 billion people and relatively limited medical resources. It has quarantined travellers on suspicion of contact with infected people and ordered schools to test students' temperatures.

The Health Ministry says around 3,700 cases of swine flu have been confirmed on the mainland - none fatal.

China aims to have enough swine flu vaccine for 5 per cent of the public by the end of the year, and although health officials have not released detailed vaccination plans, they have said health workers, public service workers and students are priority groups.

International health experts say swine flu has not been as severe as initially feared. At least 2,185 people have died, but most cases are mild and require no treatment. Worries remain that a rash of new infections could overwhelm hospitals and health authorities, particularly in poorer countries.