Zeng Gang, a researcher with Beijing-based Sinovac, said the company’s vaccine was able to provoke an immune response – indicating it could be effective at preventing Covid-19 infection – in a trial that included children aged three to 17.
Most adverse reactions were mild, Zeng said, with two children reported to have experienced a higher fever, although further details were not provided.
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Antibody levels provoked by the vaccine were higher than those seen in adults in earlier clinical trials, Zeng said at an academic conference in Beijing this week, according to Reuters.
The results were based on early and mid-stage trials that included more than 500 children. The trials began in October in Hebei province, northern China, and children were given either a low or medium-dose regime, or a placebo, according to a clinical trial registration.
Sinovac has not released detailed data and the findings have yet to be peer-reviewed, but Zeng’s comments came with several vaccine developers expanding their data on more vulnerable groups, including children, as jabs are administered for adults in many countries.
Carrying out such trials and releasing initial findings is a positive step as countries try to vaccinate enough of their populations to control the disease, according to immunologist Kylie Quinn, a vice-chancellor’s research fellow at RMIT University in Australia.
“You do have to include children in your strategy in the longer term if you’re aiming for really robust community-based protection [from Covid-19],” said Quinn, adding that in communities in which a high proportion of adults were vaccinated but children were not, the latter could become a pathway for the spread of the coronavirus that causes Covid-19.
“It’s really positive that these trials are being run and these results are coming through – it’s proof of principle that children can be vaccinated against [the coronavirus] and induce really robust responses,” she said.
Children are considered less at risk from Covid-19 than adults, because they typically have a mild illness or no symptoms at all if they become infected with Covid-19. There have been rare cases of a serious inflammatory syndrome associated with Covid-19 in children. New vaccines will normally be studied and approved for children after safety and efficacy is established in adults.
Some vaccine makers are running larger, later-stage clinical trials involving children or planning to do so.
US company Moderna, whose vaccine is approved in the United States and the European Union, last week gave the first doses in a mid and late-stage trial involving 6,750 children aged 6 months to 12 years old. It is also running a study in an older group of youths.
Meanwhile, over 2,000 12-to-15-year-olds have been added to a mid and late-stage trial of the vaccine made by US company Pfizer and German partner BioNTech.
Chinese state-owned biopharmaceutical company Sinopharm, which developed two vaccines that are now in use in China, has also conducted tests on the three-to-17 age range. Yang Xiaoming, chief executive of Sinopharm’s China National Biotec Group, this month said the company planned to submit data to regulators soon.
But when children may be included in vaccination campaigns remains unclear.
Wang Huaqing, chief expert on the immunisation programme at the Chinese Centre for Disease Control and Prevention, said on Sunday that decisions about vaccinations for babies and under-18s would be made based on subsequent clinical trials and disease prevention and control needs.
Naor Bar-Zeev, deputy director at the International Vaccine Access Centre at Johns Hopkins University in the US, said clinical trials for children would be likely to focus more on safety and immune response than on efficacy, and the threshold for safety would be higher than for adults because children rarely contract severe Covid-19.
“The rationale for vaccinating kids is not so much to protect them as to reduce transmission in the community, so it raises an ethical question if there is [a safety] risk,” he said. It would be important to study whether the rare inflammatory disorder suffered by some children infected with Covid-19 could also happen after inoculation, he added.
Vaccinations in China, where more than 82 million doses have been administered, have so far focused on adults, particularly those in high-risk professions such as health and transport.
Chinese health officials aim to vaccinate 40 per cent of the population by July and 80 per cent – typically considered enough to curb disease spread in a community – by the middle of next year.
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