Chinese Covid-19 vaccine found effective in children, adolescents: Lancet study

The researchers noted that immune responses among children and adolescents were higher than those measured in adults aged 18-59 years and elderly aged 60 years and older

A study published in The Lancet Infectious Diseases journal has said that two doses of the China-made Covid-19 vaccine CoronaVac are safe and produce a strong antibody response among children and adolescents aged 3-17 years. The study is based on phase 1/2 trial data of the vaccine.

The researchers recommended two 3μg doses of the Covid-19 vaccine for children and adolescents aged 3-17 years based on their results. (AP)

The randomised trial on 550 young people found that over 96 per cent of children and adolescents who received two doses of the vaccine, manufactured by Sinovac, developed antibodies against Sars-CoV-2. Most adverse reactions were mild or moderate, with pain at the injection site the most commonly reported symptom, the researchers said, according to news agency PTI.

"Children and adolescents with Covid-19 usually have mild or asymptomatic infections compared with adults. 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,," said Qiang Gao from Sinovac Life Sciences, China.

The vaccine - either 1.5 microgram (μg) or 3μg per dose or a control was given by intramuscular injection in two doses, at day 0 and day 28. Among the 550 participants who received at least one dose of vaccine or the control, adverse reactions within 28 days occurred in 56 (26 per cent) of 219 participants in the 1.5μg group. Such adverse incidences were reported in 63 (29 per cent) of 217 participants in the 3μg group, and 27 (24 per cent) of 114 in the control group.

Only one serious adverse reaction, a case of pneumonia, was reported in the control group, however, this was unrelated to the Covid-19 vaccination. In phase 1, 100 per cent of participants in both the 1.5μg and 3μg groups generated antibodies against SARS-CoV-2., the researchers said.

Stronger immune responses -- determined by the amount of antibodies produced that can neutralise the virus -- were detected among the 3μg group compared with the 1.5μg group. In phase 2, 97 per cent of participants in the 1.5μg group produced antibodies against Sars-CoV-2, compared with 100 per cent in the 3μg group. Participants in the 3μg group again produced a stronger immune response than those in the 1.5μg group, the study stated.

The researchers noted that immune responses among children and adolescents were higher than those measured in adults aged 18-59 years and elderly aged 60 years and older. The researchers recommended two 3μg doses of the Covid-19 vaccine for children and adolescents aged 3-17 years based on their results.