UK regulators have approved the Pfizer vaccine for children aged 12 to 15.
The announcement was made this morning by the Medicines and Healthcare products Regulatory Agency (MHRA) following safety testing on the vaccine.
Until now it has only been licensed for adults in the UK.
It follows a similar move by the EU's medicines agency (EMA) last week, while the governments in the US and Canada approved the vaccine for adolescents last month.
MHRA chief executive June Raine said: "We have carefully reviewed clinical trial data in children aged 12 to 15 years and have concluded that the Pfizer/BioNTech Covid-19 vaccine is safe and effective in this age group and that the benefits of this vaccine outweigh any risk."
More than 2,000 children were involved in the UK's clinical trial, the chairman of the Commission on Human Medicines said.
Professor Sir Munir Pirmohamed said: "We have concluded that based on the data we have seen on the quality, effectiveness and safety of the vaccine, its benefits do outweigh any risk.
"The MHRA will continue to scrutinise all of the suspected side effects data received through the rigorous surveillance programme in place through the Yellow Card scheme and other safety surveillance measures for all of the Covid-19 vaccines used in the UK."
He said more than 2,000 children had taken part in the study, and there had not been a single case of coronavirus in the seven days after they were vaccinated - compared to 16 in a group given a placebo.
Prof Pirmohamed continued: "In addition, data on neutralising antibodies showed the vaccine working at the same level as seen in adults aged 16-25 years. These are extremely positive results."
It will be down to the Joint Committee on Vaccination and Immunisation (JCVI) to decide whether to go ahead and inoculate this age group, the MHRA said.
Germany and Poland are both set to start vaccinating children in this age group next week, with France also set to start inoculating teenagers this month.
Marco Cavaleri, the EMA's head of vaccine strategy, last week said studies had shown the jabs are "highly preventative" for coronavirus in children.
He added: "From a safety perspective, the vaccine was well tolerated and the side effects in this age group were very much similar to what we have seen in young adults and not raising major concerns at this point in time."
The US Food and Drug Administration (FDA) described the approval for children "a significant step in the fight against the Covid-19 pandemic".
However, giving vaccines to younger people in affluent countries while many parts of the world await doses for older and more vulnerable people has raised concerns.
The World Health Organisation has urged rich countries to give shots to the COVAX scheme instead.
