China has ramped up regular supervision and spot checks on domestic COVID-19 vaccine manufacturers to ensure every single dose is safe, Chen Shifei, deputy director of the National Medical Products Administration, said on Thursday.

China has granted conditional market approval for its first COVID-19 vaccine on Wednesday evening, signaling mass production of the vaccine created by a company unit of state-owned Sinopharm is drawing closer.

Chen said the administration and local drug regulators have all intensified regular oversight over the company's manufacturing site. Competent specialists have been dispatched to monitor daily production on-site as well.

"Staff responsible for examining vaccine safety will launch regular patrol over vaccine manufacturers and conduct spot checks on vaccine products," he added.

The administration's Center for Drug Reevaluation is also cooperating with health authorities to monitor adverse reactions after injection.

In addition to strengthening supervision over the manufacturing process, the administration has improved its capacity to review and test every batch of new vaccine products before they enter the market.

"We began to build up the ability to review and release vaccines since the beginning of 2020, in preparation for the potential surge in requests," he said. "After rigorous and comprehensive examination and evaluation, we have decided to grant the right to test and release vaccine products to drug regulators in Beijing and Hubei province."

An established tracing system dedicated to tracking vaccine products in the market will further ensure the safety of all doses, Chen said.

Zhen Zhongwei, a health official who heads the COVID-19 vaccine development task force, said the safety of COVID-19 vaccines has been held as the fundamental and most significant principle in China.

All homegrown 14 COVID-19 vaccines in different stages of human trials have been proven to be generally safe, he added.