The Oxford-AstraZeneca coronavirus vaccine will be tested on children aged between 6 and 17 in a new trial.
Some 300 volunteers will take part, with the first vaccinations in the trial taking place later in February.
Researchers say they will assess whether the vaccine produces a strong immune response in children aged between six and 17.
The vaccine is one of two being used to protect against serious illness and death from Covid-19 in the UK, along with the Pfizer-BioNTech vaccine.
As many as 240 children will receive the vaccine – and the others a control meningitis vaccine – when the trial gets under way.
Volunteers who live near one of the four study sites – the University of Oxford, St George’s University Hospital, London, University Hospital Southampton and Bristol Royal Hospital for Children – are being asked to sign up.
Those interested in taking part must complete a short questionnaire.
Andrew Pollard, professor of pediatric infection and immunity, and chief investigator on the Oxford vaccine trial, noted that most children were relatively unaffected by Covid and were unlikely to become unwell with the virus.
However, Prof. Pollard said it was important to establish the safety and immune response to the vaccine in children and young people as some children might benefit from vaccination.
There are currently no plans for children to be vaccinated with the Oxford-Astrazeneca vaccine in the UK, as it has only been authorized to prevent Covid-19 in people aged 18 or over.
The Pfizer-BioNTech vaccine is only authorized in those aged over 16. The vaccine priority list also excludes anyone under the age of 16, even the clinically extremely vulnerable.
The University of Oxford said it was the first trial of a Covid vaccine in the 6 to 17 age group. It said other trials had begun but only measuring efficacy in those aged 16 and 17.