The vaccine developed by China's Sinovac. Photo: VCG

As China keeps breaking records in overall COVID-19 vaccinations, experts said that the country will soon expand the use of vaccines to minors in order to help Chinese people build herd immunity. 

According to the National Health Commission (NHC), more than 1.2 billion shots had been administered in China as of Monday. The news came along with the release of the world's first report of immunogenicity and safety of a COVID-19 vaccine tested in minors aged 3-17. The vaccine, CoronaVac, is developed by Chinese producer Sinovac, which demonstrated safety, tolerability and immunogenicity for the group and boosted public confidence in rolling out vaccinations for young people. 

CoronaVac is well-tolerated in children and adolescents aged 3-17 years, and induces a strong immune response, which is very encouraging. We will carry out further large-scale, multi-ethnic population studies in order to provide valuable data for immunization strategies for children and adolescents, Gao Qiang, general manager of Sinovac, said in a statement the Global Times obtained from the company. 

The trial results were published in The Lancet Infectious Diseases, the leading clinical infectious diseases journal, on Tuesday. 

Results showed neutralizing antibody titers induced by the 3.0μg dose were higher than those of the 1.5μg dose. The results support the use of a 3.0 μg dose with a two-immunization schedule for further studies in children and adolescents, according to the Lancet report. 

Observers believe the results of Sinovac's vaccine will inspire ongoing trials of other COVID-19 vaccines in children younger than 12 and boost public confidence in giving shots to children of that age in the race to reach herd immunity. 

But they also agreed that caution should be used to evaluate the long-term effects of the vaccine on children's development as it is still a controversial topic among global scientists and governments whether to vaccinate minors due to a lack of long-term observation. 

Given the large population in China and the threat of the Delta variant, China's top epidemiologist Zhong Nanshan estimated that it will require at least 80 percent of Chinese people to be vaccinated to reach herd immunity. 

According to the results of China's once-a-decade population census released in May, people aged 14 and younger accounted for 17.95 percent of the total 1.412 billion residents of the Chinese mainland as of 2020. 

As a whole it is workable to vaccinate minors, but this has to be done with extreme caution, especially for those at the lower ages, Zhuang Shilihe, a Guangzhou-based expert, told the Global Times on Tuesday. 

Tao Lina, a Shanghai-based vaccine expert, estimated that vaccination on minors will gradually kick off in China after July 1, the centenary anniversary of the Communist Party of China.  

Tao tried to ease parents' concerns, saying that inactivated vaccines are unquestionably safe for minors as many vaccines made with this method have been used on the group. 

Cui Gang, an official from the NHC, told a press conference on June 11 that China had authorized the emergency use of domestic inactivated COVID-19 vaccines and would organize related authorities and experts to lay out plans for vaccination of the group. 

According to a Reuters report on June 9, Pfizer would begin testing its COVID-19 vaccine on a larger group of children under age 12 after selecting a lower dose of the shot in an earlier stage of the trial.