BEIJING — China has witnessed 21 COVID-19 vaccines enter clinical trials, an official with the National Health Commission (NHC) said on June 6.

So far, four COVID-19 vaccines have been granted conditional marketing approval and three have been authorized for emergency use within the country, according to Zeng Yixin, deputy head of the NHC.

A total of eight COVID-19 vaccines have been approved for phase III clinical trial overseas, and one messenger RNA (mRNA) COVID-19 vaccine met the ethical requirements for phase III clinical trial overseas, Zeng said.