CanSinoBIO's COVID vaccine, tested at lower dosage, safe for children -study

(Corrects sixth paragraph of Sept 24 story to make clear China has approved three, not two, COVID-19 vaccines for use in people aged 3-17)

BEIJING (Reuters) -CanSino Biologics Inc's (CanSinoBIO) single-dose COVID-19 vaccine, given at a lower dosage than that for adults, is safe and triggers an immune response in children aged 6-17, results from a small trial showed.

Researchers decided to lower the dosage after a few participants developed fever and headaches graded at level 2 severity - the second-lowest of four levels. In children, the lower dose triggered higher antibody levels than the dosage approved for use in adults in China, according to the peer-reviewed finding https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciab845/6374123#supplementary-data from a mid-stage trial.

The trial recruited 150 children and around 300 adults.

The results also showed that children given one lower dose had a stronger antibody response than adults who were given a booster shot 56 days after the first dose.

But the antibody readings did not show to what extent the vaccine can offer protection against COVID-19, researchers from a Chinese disease control agency, CanSinoBIO and other Chinese institutes cautioned in a paper.

CanSinoBIO's vaccine has not yet got the greenlight for children. China has approved three COVID-19 vaccines for use in children from the age of three: its two most commonly used shots from Sinovac and Sinopharm plus a third shot from Sinopharm. Vaccinations have yet to begin for those under 12.

The paper said the booster shot for CanSinoBIO's vaccine improved antibody responses in participants of different age groups, especially for older adults.

But cellular responses, another important part of human immune system, were not boosted by the second shot and researchers said a wider interval than 56 days should be considered.

(Reporting by Roxanne Liu and Ryan Woo; Editing by Edwina Gibbs)