Teachers and students are vaccinated at East China Normal University's Minhang campus stadium in Shanghai on Sunday. [Photo/XINHUA] Inoculations in use found to have a good neutralizing effect on strains China is advancing the development of COVID-19 vaccines against variants of the novel coronavirus, and experiments have shown the inactivated vaccines currently used in the country are effective against them. Zhang Yuntao, vice-president of China National Biotech Group, a subsidiary of State-owned pharmaceutical giant Sinopharm, told a news conference on Sunday that 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. Three inactivated vaccines have won conditional approval for market use in China. Two were developed and manufactured by Sinopharm and the other by Sinovac Biotech. Zhang said virus mutations will always occur and cannot be prevented, but small mutations will not alter the effectiveness of vaccines. Various COVID-19 variants have been identified since late last year. While no evidence has emerged that they cause more severe illness in the majority of infected people, they were found to be more contagious. Gao Qiang, general manager of Sinovac Biotech, told the news conference that 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. The two executives said they have gained rich experience in vaccine research and development and will be able to respond quickly and effectively to mutant strains. Separately, China had administered more than 100 million doses of COVID-19 vaccines by Saturday, the National Health Commission said. 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, commission official Wu Liangyou said. Beijing and Shanghai have started vaccinating people over 60 who are in good health and those who have chronic disease, Wu said. Zhang said 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. Wang Huaqing, chief vaccination planning expert at the Chinese Center for Disease Control and Prevention, said although there is no comprehensive late-stage clinical trial data on vaccination of people under 18, it will be obtained as clinical trials progress. China has given consideration to vaccinating people under 18, including newborns, and it will continue to improve its vaccination plan based on the epidemic situation and clinical trial data, he said.