China has approved its first domestically developed mRNA vaccine against COVID-19, CSPC Pharmaceutical Group Ltd says, a major achievement in a country that has declined to use foreign coronavirus shots to support domestic research.

China, whose home-grown vaccines are seen as less effective than the Moderna and Pfizer-BioNTech mRNA shots, has been racing to develop vaccines using messenger RNA (mRNA) technology since early 2020.

The long-awaited approval comes as infections have fallen sharply across China since it suddenly dropped its strict "zero-COVID" curbs in December, making the sales outlook for the newly approved vaccine moderate.

But it would give China an additional option to tackle future outbreaks and a base for development against newly emerging variants, scientists said.

The news of China's first successful mRNA vaccine did not generate much buzz in domestic social media on Wednesday, as the country has returned to normal and its borders have re-opened.

Its top leaders declared a "decisive victory" over COVID-19 last month.

CSPC said its vaccine trials showed adverse effects were substantially lower in an elderly group compared with an adult group, which could help China as it has stressed the need to focus on protecting its vulnerable elderly population.

The company said its independently developed mRNA vaccine SYS6006 targets some major Omicron variants and its booster dose showed good neutralisation effect against Omicron subvariants BA.5, BF.7, BQ.1.1., XBB.1.5 and CH.1.1. in clinical trials.

In a study of 4000 participants from December 10 to January 18, when China was experiencing a surge in infections, the vaccine showed efficacy of 85.3 per cent 14 to 28 days after a booster vaccination.

CSPC did not say how many doses it plans to produce.

It said the vaccine could be stored at 2C to 8C for a long time.

"The group has built a good manufacturing practise-compliant production plant (for the vaccine)," it said in a statement.

"Key raw materials and excipients are produced by the group, which enables independent control in the supply chain and significantly lower production cost."

The firm won emergency approval for clinical trials of the mRNA shot in April last year around the same time as CanSino, another China-based company that is testing an mRNA Omicron booster shot.

CSPC reported a rise of 8.7 per cent in 2022 net profit on Wednesday, helped by several newly launched generic drugs included in China's drug procurement program.

Its shares rose as much as 7.7 per cent after the result and news of the approval.

David Heymann, an infectious disease specialist, said "mRNA vaccines are an important new technology and will play a major role in future to prevent infections".

World Health Organisation officials have in the past described mRNA vaccines as a "very solid option" for countries including China, particularly for vulnerable populations and for use as boosters.

Heymann said it was now important for CSPC to share its data on the vaccine with the WHO so the United Nations agency can also assess the shot for use in international markets.