Novartis said it was ready to produce one million doses of the vaccine before the end of the year in a bid to blunt the spread of swine flu which has already claimed at least 2,185 lives.
The drug giant said it was in talks to supply 35 countries with the new vaccine and had signed deals worth 979 millions dollars (685.4 million euros) to supply the US government.
China earlier Thursday granted approval to its first homegrown vaccine, which producer Sinovac says is effective after only one dose.
"The Sinovac (A)H1N1 vaccine is officially approved," said the head of the State Food and Drug Administration's drug registration department, Zhang Wei. Nine other Chinese companies were developing swine flu vaccines, he said.
The World Health Organisation praised China's research and said it could become the first country to protect its population against the pandemic.
Until now experts had maintained that two doses of vaccine would be necessary to protect against the A(H1N1) infection, straining limited vaccine supplies.
But clinical trials of the Novartis drug and of the Chinese vaccine showed that single doses could work, easing fears raised by the World Health Organisation (WHO) of a dangerous shortage of flu vaccine in the coming months.
"The pilot trial results are encouraging," said Andrin Oswald, chief executive of Novartis Vaccines and Diagnostics, referring to a trial of the vaccine conducted by Leicester University in Britain on 100 healthy volunteers aged 18 to 50.
While "two doses seem to provide better protection, one dose ... may be sufficient to protect adults against swine flu," he said.
More than two dozen pharmaceutical companies around the world are racing to test, produce and ship vaccines before the global swine flu pandemic enters an expected second wave later this year.
Last month WHO chief Margaret Chan said that vaccine supplies would be "extremely limited" in coming months, but one-dose drugs would help alleviate that concern.
"Initial information is encouraging and indicates that where supplies are limited because of restricted production, one-dose per person vaccines will provide population protection against swine flu," said Andrew Weiss, pharmaceutical company analyst at Vontobel Bank here.
Approval of the Sinovac vaccine came just days after China's health ministry warned of a potential mass outbreak as hundreds of millions of students went back to school this week with the winter flu season looming.
The ministry said China had confirmed 3,981 cases of swine flu as of Wednesday, but no deaths.
But following the vaccine tests, the WHO said China was could become the first country to vaccinate its people.
"The Chinese were very rapid on this, and we can congratulate them for having shared their trial results with us," said Marie-Paule Kieny, who heads the UN health agency's vaccine research.
It is now "likely that China would be the first country to vaccinate its population" against the flu.
The agency says 2,185 people have died worldwide after contracting swine flu which has now been detected in nearly every country in the world.
An Albanian heart patient suffering from swine flu died in an Athens hospital on Thursday and Norway registered its first death from the disease.
Meanwhile the US Centers for Disease Control and Prevention said it would announce details on Thursday on how it will deal with the spread of the virus as the flu season approaches.
Most Americans are confident their government can prevent a nationwide epidemic, according to a new poll conducted by CNN/Opinion Research Corporation.