China has signed up to a deal to ensure future Covid-19 vaccines are distributed to developing countries, the biggest economy yet to join the World Health Organization-led bid to control the pandemic.

The COVAX pledge to get vaccines to poorer nations as soon as they are developed aims to head off fears rich countries will limit distribution of game-changing medicines made by their pharmaceutical companies.

The deal gives China, the country where the virus first emerged, a prominent role in the global effort to share vaccines with less-developed countries.

China joined COVAX to "honour its commitment to turn Covid-19 vaccines into a global public good," foreign ministry spokeswoman Hua Chunying said Friday of the October 8 agreement.

She gave no details on how much money China would commit to the deal, which has a fundraising goal of $2 billion and aims to provide 92 low and middle-income countries with a future vaccine.

Chinese vaccines "will be provided to developing countries as a priority", Hua said, adding Beijing hopes "more capable countries will also join and support COVAX".

Superpower rival the US has not signed up to the deal. 

China is racing to find a vaccine, with Beijing making bold predictions on its rollout before the end of the year.

Hundreds of thousands of Chinese soldiers, emergency staff and overseas workers have already been injected with vaccines -- although the leading contenders are yet to complete clinical trials.

Beijing is facing a storm of foreign criticism over its early handling of the pandemic and has been trying to reframe perceptions of its role in Covid-19, which emerged in the central Chinese city of Wuhan.

China has paraded its success in controlling the pandemic inside its borders. 

Tens of millions of people returned to work on Friday after a long "Golden Week" domestic holiday seen as a test of consumer confidence, cutting a stark contrast to many Western nations afflicted by rolling lockdowns and travel restrictions.