China had administered more than 100 million doses of COVID-19 vaccines by Saturday.
Beijing and Shanghai have started vaccinating people over 60 who are in good health and those who have chronic disease.
The country will actively and prudently advance the COVID-19 vaccination of people over 60 and those who have chronic disease, based on the effectiveness of its mass vaccination campaign.
China National Biotech Group will start consultations with the National Medical Products Administration on the vaccination of those aged between 3 and 17, and it is expected to start soon.
The company started early and mid-stage clinical trials of vaccinations for people in that age group in Henan province last year, Zhang said.
The trials have shown that the vaccine's safety met expectations, and data on its effectiveness has also been obtained, he said.
Researchers have been testing the antiviral-mutation ability of the inactivated vaccines.
By using data from mid-and late-stage clinical trials in China and overseas, researchers have conducted experiments on a dozen variants, including those found in South Africa and the United Kingdom, Zhang said.
The experiments have found that the antibodies produced by the two inactivated vaccines have a good neutralizing effect on all the tested strains, he said, adding that such experiments are continuing on strains found in Brazil and Zimbabwe.
The company has started research and development of vaccines against the variants discovered in South Africa and Brazil.
Based on earlier cross-neutralization research on mutated strains found in 10 countries, its vaccine has proved to be effective, he said.