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A staff member presents samples of the inactivated COVID-19 vaccine at Sinovac Biotech Ltd, Beijing, March 16, 2020. [Photo/Xinhua]
The national COVID-19 vaccine developed by Sinovac Biotech is safe and can cause a strong antibody response in people aged 3 to 17 years in early and mid-stage clinical trials, according to a study recently published in a medical journal.
The study is the first in the world to examine the safety and protective effects of a COVID-19 vaccine for children as young as 3 years old. It has also happened as the spread of highly transmissible variants around the world has prompted calls for the acceleration of mass immunization, and more countries are considering expanding the use of vaccines to cover them. young people, including China.
The study, published in The Lancet Infectious Disease this week, enrolled 72 children and adolescents in the Phase 1 trial from late October to early December, and enrolled 480 participants in Phase 2 in December. Both trials were conducted in Hebei Province.
Participants received two doses of the vaccine in 1.5 micrograms or 3 micrograms per dose, or a placebo during the randomized, double-blind clinical trial.
No significant difference was seen in the rates of side effects between the three groups, and the majority of side effects were mild or moderate, with injection site pain being the most common, according to the study.
In phase 1, all vaccinated participants produced antibodies against the virus. During phase 2, a total of 96.8% of people in the 1.5 microgram group generated antibodies, compared to 100% in the 3 microgram group.
The study concluded that the vaccine seroconversion rate (the proportion of people developing neutralizing antibodies to the virus after inoculation) was over 96% in people aged 3 to 17 years.
Because a higher amount of the antibody, which signals a stronger immune response, was detected in people receiving the highest dose of 3 micrograms, the researchers said future work may focus on the use. of two doses at 3 micrograms in the younger population.
The study added that compared to adults and older people vaccinated with the same dosage, the younger population is able to develop a more robust antibody response. The finding that the immune response elicited by the vaccine decreases with age is consistent with widely used vaccines against hepatitis B, seasonal influenza and others.
The researchers said the study was small, in that the sample size was relatively small and long-term results are currently not available. The study also did not assess T cell responses, another important marker of the immune response.
They said study participants will be followed for at least a year and that larger trials in different regions and involving more diverse groups will be conducted in the future.
Researchers from the Hebei Provinces and Counties Disease Control and Prevention Centers, as well as Sinovac Biotech and the National Institutes for Food and Drug Control, jointly published the study.
Although children are believed to be less likely to develop serious infections with COVID-19, a number of countries have started to expand vaccinations amid a raging pandemic.
“A small number of them may still be at risk for serious illness. They can also transmit the virus to others, making it essential to test the safety and effectiveness of COVID-19 vaccines in groups of people. ‘younger age,’ said Gao Qiang, general manager. by Sinovac Biotech.
Zhong Nanshan, a leading infectious disease specialist, said in a previous interview that during the recent outbreaks in Guangdong Province which were caused by the Delta variant, severe cases were found in the elderly and children, pointing out the need to intensify vaccination among them.
China’s mass vaccination strategy began with a focus on people aged 18 to 59 and gradually expanded to include people aged 60 or older.
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