The US Food and Drug Administration (FDA) has authorised two Covid-19 vaccines for emergency use in children aged as young as six months.

The agency has expanded emergency use authorisations (EUAs) for the Moderna Covid-19 vaccine, also called Spikevax, and the Pfizer-BioNTech Covid-19 vaccine or Comirnaty.

Spikevax was previously authorised in the US, for use in adults 18 years of age and older. The amended EUA allows its use in individuals aged six months through 17 years.

Comirnaty had been authorised for use in individuals aged five years and above. The expanded EUA includes the use of the vaccine in children aged six months to four years.

FDA Commissioner Robert M Califf said: “Many parents, caregivers and clinicians have been waiting for a vaccine for younger children and this action will help protect those down to six months of age.

“As we have seen with older age groups, we expect that the vaccines for younger children will provide protection from the most severe outcomes of Covid-19, such as hospitalisation and death.

“Those trusted with the care of children can have confidence in the safety and effectiveness of these Covid-19 vaccines and can be assured that the agency was thorough in its evaluation of the data.”

The US FDA authorised Pfizer-BioNTech Covid-19 vaccine as a three 3-µg dose series, which was selected based on safety, tolerability, and immunogenicity data, said Pfizer.

The expanded FDA EUA is based on data from a Phase 2/3 clinical trial in 4,526 children, aged six months to four years.

In the study, the third 3µg dose at least two months after the second dose showed a strong immune response in the children, with a favourable safety profile similar to placebo.

The vaccine resulted in no new safety signals, and the frequency of adverse reactions observed in this age group was generally lower compared to children aged five to11 years.

Also, the vaccine resulted in mostly mild to moderate reactogenicity events which were temporary for both age groups with systemic events comparable to placebo.

The US FDA authorised the Moderna Covid-19 vaccine at a 25µg dose for use in young children aged six months to five years of age.

The agency authorised a 50μg two-dose regimen for children aged six to 11 years and a 100μg two-dose regimen for adolescents aged 12 to 17 years.

Moderna Covid-19 vaccine was authorised based on Positive interim results from the Phase 2/3 KidCOVE study in more than 14,000 children and adolescents.

In the study, the vaccine showed superior neutralising antibody response in the six months to five years of age group, consistent with that of young adults, with a favourable safety profile.

FDA Centre for Biologics Evaluation and Research director Peter Marks said: “As with all vaccines for any population, when authorising Covid-19 vaccines intended for paediatric age groups, the FDA ensures that our evaluation and analysis of the data is rigorous and thorough.

“In addition to making certain the data for these vaccines met FDA’s rigorous standards, the agency’s convening of an advisory committee was part of a transparent process to help the public have a clear understanding of the safety and effectiveness data supporting the authorisation of these two vaccines for paediatric populations.”