Two doses of the Covid-19 vaccine developed by Chinese company Sinovac provoke a strong immune response among children, a new study indicates.
A clinical trial of 550 young people aged 3 to 17 was published in Britain's The Lancet medical journal on Monday.
It found more than 96 per cent of children and adolescents who received two injections of the vaccine developed antibodies against Covid-19.
Most adverse reactions to the vaccine were “mild or moderate”, with pain at the injection site the most common reaction, the study found.
The vaccine, also known as CoronaVac, is made by Beijing biopharmaceutical company Sinovac Biotech.
The Sinovac vaccine has faced criticism over its effectiveness in adults. A large Phase 3 trial in Brazil showed the vaccine had efficacy of 51 per cent after two doses.
Qiang Gao, vice president of research and development at the company, said the study showed the vaccine was “well-tolerated and induced a strong immune response” among children.
“Children and adolescents with Covid-19 usually have mild or asymptomatic infections compared with adults," Mr Qiang said.
"However, a small number may still be at risk of severe illness.
“They can also transmit the virus to others, making it vital to test the safety and effectiveness of Covid-19 vaccines in younger age groups.”
Prof Bin Cao, from the China-Japan Friendship Hospital, urged authorities to consider vaccinating children against the disease.
“Herd immunity against Covid-19 is the prerequisite to end this pandemic, either through vaccinations or natural infection,” Prof Bin said in a linked comment.
“Most estimates placed the threshold at 65-70 per cent of the population gaining immunity, mainly by vaccination.
"However, widely circulating virus variants and persistent hesitancy on vaccine make this threshold difficult to reach.
"The calculation has to be revised upward and children must be covered in the immunisation campaign.”
All participants who received six micrograms of vaccine across two doses developed antibodies, the study found.
The children involved in the trial will be followed for at least another year to study the long-term effects.