US regulators have approved the Pfizer COVID-19 vaccine for use in children as young as 12.

US President Joe Biden said the authorisation is “a promising development in our fight against the virus”.

“If you are a parent who wants to protect your child, or a teenager who is interested in getting vaccinated, today’s decision is a step closer to that goal,” he said.

It comes after a trial of more than 2,260 volunteers in the US aged between 12 and 15, showing the vaccine was safe and offered strong protection.

The trial earlier this year saw 18 cases of COVID-19 in the group that was given the placebo and none among those who were given the vaccine.

It also found that the children developed higher levels of antibodies than earlier studies had seen in young adults.

Some of the volunteers also experienced the same side effects – sore arms, fever, chills, or aches – all of which can signal the immune system is being strengthened against the virus.

The Food and Drug Administration’s chief doctor Peter Marks said: “Having a vaccine authorised for a younger population is a critical step in continuing to lessen the immense public health burden caused by the COVID-19 pandemic.”

A federal vaccine advisory committee has issued recommendations for using the two-dose vaccine in children aged between 12 and 15 and vaccinations could begin as early as Thursday.

Pfizer senior vice president Dr Bill Gruber told The Associated Press: “This is a watershed moment in our ability to fight back the COVID-19 pandemic.”

Canada was the first to approve the Pfizer vaccine for those as young as 12 but Pfizer has requested similar authorisation in the European Union.

Many other countries are using it on people aged 16 and older.

Pfizer has said it will have safety and efficacy data for children aged between two and 11 in September and it plans to ask the US to extend authorisation then.

Around 46% of people in the US have received at least one dose of a COVID-19 vaccine but the pace has slowed significantly in recent weeks.