The genome of the novel coronavirus is generally stable across the globe and current mutations of the virus will not affect the potency or development of vaccine candidates, Chinese experts said on Friday.

According to the journal Nature, there are nine COVID-19 vaccine candidates in phase three clinical trials around the world, with four of the vaccines from China. Yang Sheng, deputy director of the bureau of drug registration at the National Medical Products Administration, said that all four Chinese vaccines are conducting their trials overseas with approval from foreign health authorities.

The four vaccines consist of three inactivated vaccines and one recombinant adenovirus vector vaccine, Yang said, adding that China also has seven other vaccines in different stages of clinical testing.

Because the COVID-19 vaccine is an innovative product that requires sufficient amounts of preclinical and clinical data to verify its safety and efficacy, vaccine developers need to launch third-stage human trials overseas due to China's effective control of the epidemic domestically.

The phase three trials will provide key information on a potential vaccine's ability to protect against the virus while ensuring safety. More scientific evaluation and global assessment will also be based on results from this testing stage, according to Yang.

Zhang Xinmin, head of the China National Center for Biotechnology Development, said vaccine developers are closely monitoring any mutations in the virus' genome, and they have found the virus to be highly homogeneous across the globe.

"The virus' mutations have no real impact on vaccine development," he said. This is due to most vaccine candidates using the genetic material for the virus' spike protein to provoke an immune response, and that ingredient is very stable, he added.

At year's end, China is expected to have the ability to produce around 610 million doses of COVID-19 yearly, and the annual production capability is expected to reach 1 billion doses next year, said Zheng Zhongwei, head of China's COVID-19 vaccine development task force.

However, it is unrealistic to expect that ordinary people will be able to get their shots immediately when the vaccine hits the market, as there are high-risk and vulnerable groups, including medical staff members, overseas workers, the elderly, and children that should be prioritized, officials said.

"With vaccines being public goods, their price will definitely fall within the acceptable range for the general public," Zheng said.

When asked about the strength and duration of protection of the vaccine candidates, Zeng Guang, chief epidemiologist at the Chinese Center for Disease Control and Prevention, said the novel coronavirus was discovered only nine months ago, and there is still much to learn about the virus.

"So far, not a single vaccine has been proven to be fully effective against COVID-19, and most people are not expected to get vaccinated this winter or early next year," he said.

Therefore, people should still wear masks, wash hands and maintain social distancing, especially when other respiratory diseases such as the flu are more common in the winter, he added.