The US drug company Moderna has begun studying its COVID-19 vaccine in children aged six months to 11 years old, writes BBC.

Moderna is the first US manufacturer to test its vaccine on infants.

The company plans to enrol some 6,750 children in the US and Canada for the trial.

The inoculation of children and young people is seen as critical to achieving the level of herd immunity necessary to halt the pandemic.

While the risk of children becoming seriously ill from the virus is smaller than for adults, there is still a risk of transmission - especially among teenagers.

"This pediatric study will help us assess the potential safety and immunogenicity of our Covid-19 vaccine in this younger age population," Moderna CEO Stéphane Bancel said.

Both Moderna and Pfizer began testing their coronavirus vaccines on children aged 12 years and older last year. Results on these trials are pending.